Plant Clinic

Archive

Acacia (Mimosa), grown from seeds
Q. Please can you tell me about Mimosa? I have been given some seeds.

A. Mimosa (botanical name Acacia) hails from the southern hemisphere, predominantly from Australia. This give you a very big clue about the situation it likes, i.e. sunny, hot, tolerant of low rain levels, in fact intolerant of wet ground. The ideal situation for an Acacia would be well-drained soil and full sun. Pruning can be difficult and is best done annually immediately after flowering. It does not regenerate well from old wood.
There are several different species that are best suited to garden cultivation. The three most popular are Acacia dealbata (probably the best known variety), Acacia pravissima which has strange triangular foliage and a weeping habit, and Acacia baileyiana 'purpurea' which has gorgeous blue-grey foliage. All of these varieties have the traditional, fluffy yellow flowers. The toughest variety is A. pravissima while baileyiana 'purpurea' needs the most protection. Suitable for most gardens except the most exposed and the coldest.

Acid soil, how to correct
Q. My vegetable patch has a very acid soil. What can I do to improve it, and do I need to worry about the rest of the garden becoming too alkaline?

A. Traditionally, vegetable gardens are neutral or alkaline. So, if you have acid soil you will need to correct this by the addition of garden lime. It’s important to only apply it at the rate stated on the packet. This is a definite case where you can have too much of a good thing! You will also need a simple soil testing kit to give you a starting point. If you’re putting lime on your vegetable patch it shouldn’t affect the rest of the garden unless you do it on a very windy day. Depending on the level of acidity, annual applications will probably be needed. Correcting the pH of your soil is essential with certain vegetable groups, especially Brassicas.

Agapanthus, sowing seeds
Q. I've just been looking at your website, and I'm wondering if you could give me any advice on the seed propogation of agapanthus. I've removed the seeds from the old flower heads and want to sew them in samll pots. Can you give me any advice or is it fairly straightforward? Is it ok to sew them immediately or should I wait for the seeds to 'dry' a bit, and is there any special seed compost that I should use? Any help at all that you may be able to offer I would be very grateful for. I don't live by the sea, I'm actually in Oxfordshire, but I'm quite successful at growing agapanthus in terracotta pots, and now want to try and increase their numbers.

A. If the seed has been collected freshly from the plant, then it is generally best stored until the spring. What I normally recommend is that you cut the seed heads, stalk and all, put the heads into as big a paper bag as you can get, very loosely tied around the neck so that any seed that falls will fall into the bag but so that plenty of air ventilation can get to them. Don’t be tempted to hang them up in a greenhouse, because whilst you might think that’s dry, it is actually damp. It’s far better to hang them up in a spare bedroom or somewhere like that so that they actually dry and cool and the seed can fall. Almost without exception, most seed of perennials is best sown in the spring in this country when seed is inclined towards germination and plants are inclined towards growing. Whilst in nature seeds will drop and lie dormant all winter and then start germinating in the spring, you don’t get many species that will germinate in the autumn because the temperature is too low. So, I personally would advocate doing it in the spring, I would recommend that it is sown into a proper seed compost, probably a John Innes seed compost: failing that, a multi-purpose one will do because they’re fairly low in feed.

You treat them pretty much the same way as you would any other seed, really, in that you sow them and cover them roughly the same depth of soil as the seed is big. So the general rule of thumb is, if your seed is like dust, you don’t cover it: if your seed is a couple of grains of sugar big, then a couple of grains of sugar depth of soil is what you put on top of it. Water, heat and off you go!

Agapanthus are relatively easy from seed – you’ve only got to visit the Isles of Scilly and see how they’ve self-sown all over the place. Nature doesn’t need a helping hand with those ones! Happily go ahead and sow some seeds, but be prepared for disappointments as well as pleasures, because anything that comes from seed is unlikely to be true to the parent, particularly if the parent is a named variety: you will get variations on a theme and you need to be aware of that before you start. With seed-raised plants but it's always fun, you’re never sure what’s going to come out. The offspring of two white agapanthus may not be white, because you can guarantee that some pain-in-the-a**se bee has travelled from a blue one to your white one. You can get all sorts of progeny (a bit like Hellebores, terribly promiscuous little beasts!).

Agapanthus not flowering
Q. How do you persuade Agapanthus to flower? I have some three-year old plants in pots.

Well, you don’t go out and beat them over the head with a stick! Generally, Agapanthus flower better when they are root-restricted, but not always. It’s more important to get the food into them, than to worry yourself overly about ‘is it in a big enough pot, am I doing this or that or the other wrong?’ The important thing is food: they need to have food in the summer and into the autumn in order to produce the dormant flowering spikes for the following year. But you can more or less encourage them if you start feeding them now, you can usually encourage a good flush of flowers for the summer, but you want to make sure that you give them a reasonably high potash feed to encourage flowers to come. People seem to think that they need to be pot-bound to flower well – in which case, I have to ask the question, ‘How do all the ones that are in people’s gardens do so well, where they’re not pot-bound at all?’ You do need a certain amount of maturity with them, admittedly, but having said that, they would do well more or less wherever they are, so long as they’ve got the basic conditions they need, which are: reasonably good, well-drained soil, in full sun. They will not tolerate shade and won’t do well there at all – that will stop them from flowering. In fact, if the clumps get over-congested that can also stop them flowering because the bulbs aren’t getting enough nutrients, so if it’s an oldish clump then that can benefit from being divided, split up and replanted – but then it can take a couple of years to settle down and start to flower again. There is no hard-and-fast rule, unfortunately. I can’t wave a magic wand and say ‘poof’ and your Agapanthus will be in flower! Patience is a bit of a virtue with them. They will flower, and my main recommendation is to feed-feed-feed.

Annuals sown as biennials
Q. Last autumn I bought a collection of annual flower seeds and sowed them in trays in the greenhouse. They came up and thrived at first but then they became leggy and some of them died. What is the best way of growing annuals as biennials?

A. The seedlings need to be pricked out and potted on. Then grow them on in the greenhouse through the winter. Keep the temperature down but frost-free. Keep them growing and then harden them off and plant out in the spring.

Aphids on conservatory vine
Q. We have a vine growing in our conservatory. It was there when we moved in, so it's over twenty years old. Each year it produces grapes, but each year it is smothered in aphids which ruin the grapes and attract flies. What can we do?

A. You need to tackle the aphid problem - but as it's in a conservatory I suggest a biological control, e.g. the more sadistic of you can buy Lacewing larvae! Or you can spray with a non-toxic contact spray: I would recommend 'Just Bug Killer'.

Aphids, avoiding them in greenhouse
Q. Now that we’re all beginning to think about sowing things in the greenhouse or polytunnel, is there any way to prevent Aphids from turning up?

Good hygiene is of paramount importance when it comes to preventing the spread of insects and disease in any greenhouse, and before you start putting anything in there for the spring it is vitally important that you have a really serious spring-clean in there: Jeyes Fluid washed down under the glass, over the woodwork, into every ‘crook and nanny’ that you’ve got in there, because any overwintering insects will then be disposed of and that will give you the best start possible. Any odd pots and trays, get them out – don’t use your greenhouse as a dumping ground – get them out of there and give your greenhouse a nice fresh start. If you’ve got soil in the greenhouse, then make sure you treat the soil as well with Jeyes Fluid and kill any overwintering bugs that may be living in the top of the soil. That’s step one. Step two, when you start putting your plants back into the greenhouse, if you have been overwintering things in there like Begonias, Fuchsias, Geraniums, then when you do your spring clean, sprinkle those plants as well: take them out, knock the top of the soil off, knock all the dead leaves off and again, drench them with insecticide before you put them back in. Make sure that everything is as clean as it can be. When you start sowing your young plants, keep a close eye on them and watch them all the time for the first signs of Greenfly – that’s certainly the most important thing. A lot of people don’t look at their plants enough, so they tend to miss the first signs and once they get a hold that’s when they become little beggars to get rid of, unfortunately. So hygiene and vigilance are probably the most important weapons you’ve got.

Apples for Cornwall
Q. Please can you suggest some varieties of apples that will grow in Cornwall?

A. This depends to what end you want to use your apples. Cider varieties were always more traditionally grown in the west country, but there are some good dessert varieties as well. Ones I would recommend include Cornish Aromatic and Cornish Gillyflower, both are excellent traditional varieties. Of the more modern varieties, 'Meridian' has an excellent flavour, 'Irish Peach' has a distinctly aromatic flavour. And in cooking apples, of course Bramley is the best known, but I would say that 'Newton Wonder' and 'Grenadier' are more reliable in Cornwall. There are plenty of other varieties that do well, I haven't got enough room on this website to list them! A couple of useful sites to visit include the National Trust at Trelissick, Duchy Nursery near Lostwithiel and Thornhayes Nursery in north Devon.

Apples falling early
Q. Why do apples set on my apple tree but then most or all of them fall off in June?

A. There is nothing you can do to prevent it: it is a safety-valve for the plant to avoid carrying too many fruits. It can be caused by dry weather in late spring: but if you know how to prevent that you're a better man than Gunga-Din. Thinning the fruit may help.

Architectural plants for large borders
Q. Please suggest some big, bold plants for large borders.

A.Ignoring trees and larger shrubs, there are many gloriously impressive perennials to really 'lift' your border. A few to whet your appetite are: Cynara carduncularis; the Globe Artichoke with massive silvery grey cut foliage and magnificent thistleheads (to make a Scotsman jealous); Verbena bonariensis, which grows about five feet tall and creates a purple haze of semi-everlasting flowers; Hedychium in variety, but particularly "Stephen", is a member of the Ginger family, with deliciously scented flowers and leaves that will make you dream of Madeira and the tropics with its lush foliage. In the same vein, the Cannas provide vibrant colour, lush foliage and dramatic lines in any border. Also in the autumn, Rudbeckia herbsommer, reaches a magnificent seven feet of brilliant yellow flowers. Finally, I would heartily recommend Tetrapanax papyrifer which has leaves up to three feet across… you can just imagine lying out in the sun being fanned by a willing slave….

Asparagus, how to make an Asparagus bed
Q. How do I start an Asparagus bed?

A. Asparagus beds consist of very well-drained soil but rich and deep. A sandy soil does best for them and they really do benefit from digging in plenty of well-rotted organic material before you start. You must then exercise enormous restraint and not be tempted to pull them in the first two years after planting.

Bamboos for exposed sites
Q. Please could you suggest some Bamboos for an exposed position on the edge of a field?

A.The tougher bamboos can be tricky because sometimes they a little bit on the invasive side and you really need to be very careful that you’re not planting a problem for yourself if it’s going to shoot and sucker too badly. One of the toughest ones is Phyllostachys bissettii which is a very tough bamboo that will tolerate coastal and inland winds and makes a very good screen: but a lot of the Phyllostachys spread by underground shoots and if you don’t want them running into a neighbour’s ground you may need to put up some sort of a physical barrier down in the ground before you plant them. The Pseudosasas are also another good group of bamboos, bigger leaves, maybe not quite so tall but they do produce a good, dense screen. It’s not easy to identify an un-named variety, it’s best to take a photograph and ask an expert. But have a look at the Fargesias, which are big, busy and not very invasive: they do really quite well.

Badgers damaging lawns
Q. How do I discourage badgers from digging holes in my lawn?

A. The only way to distract a badger is to confuse his nose - any physical barriers you put in his way he'll take great pleasure in demolishing. Try using something as simple as Jeyes Fluid on the entry point to your garden, and keep everything crossed.

Bananas from seed
Q. I've always wanted to grow banana trees from seed, but they never seem to germinate. Please could you suggest easy types and tell me the best method?

A. The best variety to grow is Musa basjoo. Make sure that the seeds come from a good source, e.g. Chiltern Seeds catalogue. They do need heat to germinate and will probably need to be in a propagator. Follow normal procedures from then on.

Bay, how to propagate
Q. How do I propagate Bay?

A. Bay, which is Laurus noblis, is best propagated by semi-ripe cuttings taken in mid- to late summer. These should be trimmed and treated with a rooting compound as with any other cuttings, and can be maintained either in a propagator or in a sheltered position outdoors. A note of caution - they can be quite slow to root. However, another method is to look around the base of an established Bay for suckers which can be separated from the main plant by the judicious application of a sharp spade.

Beans for drying and storing
Q.Is it possible to grow beans such as soya for drying and winter storage?

A. The traditional beans for drying have usually been peas or broad beans, but I have to be honest and say that I'm not familiar with the vagaries of soya beans in this country. But most legumes were traditionally stored dried for long keeping and reconstituted for cooking by soaking in water.

Magic Bean - what is it?
Q. Last Christmas our son had a ‘Magic Bean’ in his stocking. This bean had instructions for planting and a promise of a ‘message’ inside, and sure enough when it came up it had the words ‘Magic Bean’ etched into its seed leaves. Anyhow we grow this bean on in a pot and stood it inside the big window of our sitting room. For the last year it’s been growing and growing but with no sign of flowers. Have you any suggestions as to what sort of bean it is and when it will stop and flower?

A. You have me stumped, here! As for variety, I haven’t the faintest idea, and I’d love to know how they get the little message in the first pair of leaves. I have now idea what sort of bean it is but it’s probably been selected for its ability to be ‘manipulated’, shall we say, to have the message put on the first pair of leaves. So I wouldn’t be able to hazard a guess as to variety. If it’s been grown in a pot indoors, it may be that it’s not getting enough light for it to start to flower, but most beans I’ve known would grow very happily in any situation and would start to flower, so I strongly suspect this is one that has been modified in some way, and I’m not entirely sure that you’ll ever going to get much of a crop of beans out of it, is the answer to that. I’ve never heard of it and I’m absolutely fascinated, I’ve got to say, but I think you’ve got me beaten!.

Fibrous rooted Begonias, how to propagate
Q. I have indoors a small, fibrous-rooted Begonia about six inches high. What’s the best way to propagate it and when?

For the fibrous-rooted Begonias, the only way for you to propagate it sensibly is from cuttings. You need to wait until your plant has got some side-shoots on it: if it’s only got one central stem at the moment, pinch it out – if you pinch it back with two or three sets of leaves that can be your first cutting – and then as it shoots out sideways you can take side cuttings off it as and when you want to, really. They’re very, very easy to do. Commercially, they’re done from seed, but the seed is like dust and the word ‘gold’ added on the front is quite applicable! It’s very, very fine seed and it’s quite difficult to get them to germinate without proper conditions like a propagator, so I would normally recommend buying plugs or growing on a young plant. As I say, if you’ve got a particular colour you like, then propagating by cuttings is just as easily done.

Birds, gardens for
Q. We have quite a big garden. Can you suggest some plants to encourage birds?

A. Without taking up all the page - anything with berries will provide valuable food in the autumn, but it's worth bearing in mind that the birds will take red berries first, orange next, and yellow and pink will be last choices! You'll also need to consider providing evergreens for winter shelter. Plants that attract insects will also encourage birds that feed on them. A very good book to give you some hints would be 'Gardening for Wildlife' by George Pilkinton at £4.95, published by Alfresco Books.

Bog garden, how to create
Q. How can I create a bog garden?

If you want to create a 'boglet' or damp area in your garden, the best way of doing it is to excavate the area that you want to make much moister. Get either a heavy-duty plastic sheet or an old pond liner – it doesn’t have to be intact but it needs to be relatively impermeable. Make sure you dig the hole deep enough so that you can dig holes and plant plants in it! – there’s nothing worse than just putting it six inches under the soil, that’s no good at all. It really needs to be 18 inches to two feet down into the ground. Bury your liner in the hole and then perforate it, don’t have it absolutely 100% waterproof because all you’re going to do then is create a slurry-pit! You want the water to be able to seep away but at a slower rate. Then backfill it with soil, don’t use posh compost or anything like that, use ordinary good garden soil. If your own soil’s quite sandy then you might look at bringing in some topsoil from another part of the garden or even buying in a some topsoil, so that you can get a more loamy compost only into the bog area. Then basically just backfill it all up again. You can work some peat in if you want to because peat is a natural bog substrate. Really once you’ve done all of that you can start planting subjects that are going to enjoy a more moist situation. You can then soak the area (although given your average Cornish winter you won’t have to worry about it, but then again, given the average Cornish spring at the moment you may have to!) and the water will be retained in there for a lot longer. It will gradually seep out so it won’t get sour at the bottom – that is the risk if you put a completely impermeable membrane in, it can go sour and soggy right at the bottom. So the water will gradually seep out, it’s not going to rush away. You can top it up occasionally and you have your own happy little boglet. One converse point: if you’ve got a garden where the soil isn’t very soggy but it isn’t very dry ‘neither fish nor fowl’ but you want to make an area moister, try incorporating more peat and organic matter into the soil and anything that will retain moisture, rather than adding grit and drainage: that will up the moisture content in the soil and will increase the range of species you can grow.

Buying bedding plants in winter
Q. There are bedding plants in a well-known chain store. Surely they can’t really be put outside in this weather? (mid-February)

A.Very true, they can’t! Unfortunately, a lot of nurseries and, more, garden centres, tend to jump on the early bandwagon for bedding plants. They will either sell them as these trays of young seedlings which you can take home and plant out for yourself, or in fact they’ll have bedding plants to sell. No way, José, should they be put out yet! It’s only the beginning of February, for heaven’s sake so we’ve got another two months with a risk of frost, even in Cornwall. I certainly wouldn’t even consider putting out summer bedding yet. Spring bedding, yes: Polyanthus, Pansies, Forget-me-nots, Violas – all those sort of things are fine – hardy bedding is fine, but tender bedding – you shouldn’t even be considering it yet. If you see them in the garden centres and think ‘Oh, I’ll get an early start’, the chances are you’ll be buying them again in two months’ time. I wouldn’t even consider selling summer bedding yet for at least another six weeks.

 

Black Bamboo, where to grow
Q. What is the best situation for growing Black Bamboo?

A. Quite a tolerant plant, this, but it will be happiest in moderately moist, good soil. Having said that, it is quite tolerant of a range of conditions. So it's worth experimenting with. To show the stems off to their best colour, I would recommend growing it in a semi-shadey or sunny position with a light background. In full shade you will lose the effect of the stems.

 

Black Bamboo, problem with
Q. I have a Black Bamboo which is struggling, it’s hardly replacing its leaves. Any suggestions, please?

If you’ve got a bamboo that is obviously struggling, then the chances are that there’s something deeply unhappy at the root. Depending on how long it’s been where it is, it may well be worth considering moving it to another situation. If it’s in a pot then I suspect it’s struggling because it’s in the pot – possibly drainage issues, difficult to say, but I would recommend that it is moved out of the pot and planted into the ground. Ideal conditions would be moisture-retentive, but not boggy, soil; some protection from the worst of the wind; it actually grows quite well in sunny shade, but be careful where you put it because if it’s too shadey you’ll actually lose the effect of the dark stems – you need to have a light background to show it off properly. It does benefit from fairly rich soil, so I would make sure you incorporate well-rotted compost into the soil before you plant it out, but it certainly does appear that if it’s struggling in a pot, I’d say there’s something fundamentally wrong with the conditions that it’s in.

Blackfly on broad beans
Q. Most years I get blackfly on my broad beans. Can you suggest how I can prevent it, or failing that, treat it?

A. Once you've got it, personally I prefer to use a more natural control which you should be able to get from your local centres. One is called Organic Pest Control, but the cheapest option is to buy Savona which you can then dilute and use quite safely on all food crops. Avoiding it in the first place is very difficult unless you use a complete barrier to prevent infection, e.g. horticultural fleece.

Blue plants
Q. Can you recommend some blue plants for someone who likes everything blue?

Blue-flowered plants are relatively easy, although there are those who say horticulturalists are colour-blind and their ‘blue’ is most people’s purple! One of the most popular groups of blue flowers would have to be the Ceanothus which gives gorgeous flowers in the spring and summer. Ceratostigma willmottianum is another of my favourites, and there’s a very good new variety called ‘Forest Blue’ and there’s one called ‘Desert Sky’, which are particularly lovely. I think another of my favourite groups of plants with true-blue flowers would be the Pulmonarias, which are the Lungworts – they have gorgeous flowers , very early – in the late winter, almost . They're a herbaceous plant, particularly attractive, I’m very fond of those. But probably my favourite flower would have to be the Meconopsis – the Himalayan Blue Poppy: this is a plant which my mother could always grow very well in her garden. I’ve given up trying to kill them now: I can’t grow them in my garden, they like those mythical conditions of well-drained, moisture-retentive soil. If you can grow them, they’ll love you and they’ll self-seed and they’re beautiful in the garden. If they don’t love you, you’ll end up fighting an uphill battle to grow them. So those are probably my favourite blue flowers.
Now, when it comes to foliage, that’s a little bit more tricky and I suppose really, in honesty, you’re looking at a sort of glaucous-y foliage rather than truly blue. One of the more unusual ones which is worth looking at is the Fothergilla, which is normally grown for its autumn colour, which is absolutely gorgeous and it’s a member of the Hazel family. Fothergilla gardenii ‘Blue Mist’ has lovely glaucous foliage.
Then you can look at the more Mediterranean-looking plants, particularly some of the palms: Butia armata is a very handsome, almost a blue version of the Phoenix palm with a lovely, steely-blue foliage to it. The other palm which is well-worth looking at is the blue Chamaerops: most people know the Chamaerops humilis which is a fairly hardy, dwarf fan palm, but the blue version of it, Chamaerops humilis 'Cerifera' is, again, very handsome to look at and quite striking. It stands out well and is very popular with landscape designers for doing coastal gardens. Those ones work particularly well, so you’ve got quite a good range.

Blueberries in exposed sites
Q.How salt-tolerant are Blueberries? Would they grow in open ground?

I wouldn’t say that Blueberries are my best choice for growing in an open position. Of paramount importance for Blueberries is the soil – it has to be extremely acid and it needs to be moist, so it doesn’t want to be in soil that dries out readily, particularly during the summer. And in all fairness, unless you live in a very acid, almost boggy moorland area in Cornwall (or most coastal areas of the country) they are generally best grown in pots where you can control the environment for them much more easily. But it’s not one I would recommend for an exposed coastal situation. Having said that, Billberries, which grow wild on moorland areas, have been known to grow down to Scottish sea lochs, along the cliffs and coastal areas of Scotland. So, I don’t really see any reason why Blueberries shouldn’t, it’s simply that I haven’t seen them in that situation. But as I say, the critical thing is the soil and the moisture.

Bonsai trees, how to start a collection
Q. What’s the best way to start a Bonsai collection?

Probably the easiest plant to start off a Bonsai would be a small, deciduous tree. The purists would start them off from seed so that they could start training them from a very young plant, but you can buy a young whip or a young seedling quite easily; and if you get something that is very flexible like a birch you can start to twist it and bend it to your will quite easily from a young plant. Some of the favourites that are used are in fact Birch and also Acer campestre – the Field Maple – is a popular one, and of course the Pines. Unless you’re a dab hand at it you can find you’re stripping the bark off half one side of it so that there’s this tiny strip of bark supporting life at the top of this tree. So you can very easily buy a seedling of a tree, or you can find seedlings growing around in your garden, very often, and you can dig up one of those and start off with them. But don’t go for something like Beech or Oak because they’re too slow-growing: if you want to get a result quickly with your first Bonsai, go for something a little bit quicker. And of course, if you buy something like a dwarf conifer, particularly one of the Chamaecyparus obtuse group of conifers, they’ve got naturally twisty, bendy stems and they have a slightly Japanese-y look; with judicious pruning-out you can start off with a fairly ordinary-looking conifer and, half an hour later, end up with something that looks like it’s spent a hundred years growing into that twisted shape. So that’s quite a fun way to start, as well. You need to trim the roots and you do need to splay the roots out as well: they don’t grow Bonsais in the sort of pot you’d grow a plant in ordinarily, they’re grown in wide, shallow pans which, again, restricts the height and growth. But if you’re taking a plant that’s been established in a pot and you’re wanting to splay the roots out, be careful not to damage them too much, because obviously you are pulling the root system apart – gently does it! As for compost, you can buy Bonsai compost and it’s probably best to do so because they need a very low nutrient compost: you don’t want to encourage vigorous growth, so get the right stuff for it. If you go for something hardy, they can live outdoors. You can also find houseplants done as Bonsais and they must be kept indoors, but virtually everybody who grows Bonsai, if they put them outdoors they put a lid over the top – so they won’t be heated and very often they haven’t got sides on whatever structure they’re in – a bit like a leanto, I suppose; but they do try to keep the worst of the rain off because they haven’t got the root system to support the same level of rainfall that most plants could cope with.

Box, fungus in
Q. I saw something recently on a TV gardening programme about Box hedges being affected by a fungus. As I'm intending to plant a box hedge I am wondering whether this is a new problem and whether it can be controlled?

A. The problem you see is called Box Blight and has been around a long time. There seem to be two different types and there are varying opinions on how best to treat it. Basic treatment involves cutting out affected areas, and the plant will normally regenerate. Obviously in an established hedge this can be dramatic but it may be possible to spray preventatively with a fungicide. It isn't usually a serious problem but if you've got a knot-garden it can cause serious problems. There are no quick or easy answers, I'm afraid.

Brachyglottis repanda, problems with
Q. I have a Brachyglottis repanda. It’s been living outside, it looks extremely miserable with purple marks and holes in the leaves. Any sugguestions?

Brachyglottis repanda is one of the less hardy members of the family and really does need to be in a very mild, frost-free coastal area – which, unfortunately, we can’t always provide to the extent that we would like to. Now, if it’s still got foliage on this is a good sign; if the foliage is marked and spotted and purple and it’s looking sorry for itself, I’m not in the least bit surprised, given the winter that we’ve had. What I would suggest is, if it’s in a container, then I would be tempted to give it a spring holiday, if you have a greenhouse or a conservatory, take it indoors, give it a bit of TLC and it will, hopefully, perk up again. If it’s in the ground outdoors, then what I would probably recommend is that you have a good look at the plant, if the stems are looking relatively OK I would give it a light haircut – don’t cut back into old wood, just take off some of the tips, and encourage it to send out new shoots. If it can do that, then hopefully it will regenerate and recover. It’s been a very cold, very wet, very miserable winter and that’s almost certainly what it’s suffering from, because as I say it’s not as hardy as ones like ‘Sunshine’, ‘Monroi’ or ‘Rotundifolia’.

Burglars, plants to deter
Q. Can you recommend plants that will deter burglars?

A. In this case you can be quite vindictive without anybody being able to tell you off! In fact, police recommend it. Some good ones to consider include: groundcover roses, Berberis - especially B. x ottawensis "Superba" - hollies of all descriptions and gorse. If you're feeling really nasty, as well as wanting to create a desert effect in your garden, plant Agaves and Puyas as they have backward facing teeth. Having caught your burglar you can then select your chosen method of punishment! Basically, any prickly plant will do.

Brassicas, Club Root in
Q What can I do about Club Root in Brassicas, short of moving to another vegetable plot?

Club Root normally comes about when you have been growing Brassicas in one area for too long. It can be treated by a variety of methods. First and foremost by not growing any more Brassicas in that area for several years, so yes, rotation is one answer and would certainly be the best choice, with a minimum rotation of four years. But you can also look at increasing the lime content of your soil to help counteract Club Root. Also, incorporating Mycorrhizal fungi into the soil will help to stop it: you can now buy them from most nurseries or garden centres: they come under the trade name of ‘Root Grow’. One of the things that people sometimes do is to grow their Brassicas in pots to start with and plant them out when they have an established root system which will support them even if they do get Club Root afterwards. But really and truly, it’s good husbandry and good crop rotation which should hopefully help keep Club Root at bay.

Butterflies, encouraging them
Q. Please can you suggest some plants that will encourage butterflies into my garden?

A. To start with, the obvious and well-known one - Buddleia in all varieties. Also consider Sedum (whether Alpine or perennial variety), Clethra - Sweet Pepper, Caryopteris, Berberis (valuable for early spring pollen), Heather for all seasons, Perovskia - Afghan Sage - and virtually all culinary herbs. There are plenty more but I don't want to fill up the website with one long list!

Cannas, how to grow
Q. How do I grow Cannas? I’ve never tried before.

A. Cannas fall broadly into two categories: hardy and non-hardy. Non-hardy are probably the commonly recognised ones and are best described as ‘tropical looking Gladioli’, in that they stand up, they’ve got a big spike of flower, huge foliage with leaves reminiscent of red or streaky variegated – almost banana-like – leaves. They’re very often used, unfortunately to their detriment, in municipal planting schemes on roundabouts in seaside resorts which tends to put people off them sometimes. But for all that, they are wonderful, lush, exotic plants which will ‘lift’ any planting scheme or border, and I think are well ‘worth the candle’. If it’s those ones that you want to try growing, you generally buy them as dry corms during January, February or March. From March onwards you would buy them as a growing plant in a container. Either works just as well, it depends on you, really – your time, budget and green-fingeredness I suppose, as to which you go for. The key things to remember with all Cannas is that they like lots and lots of food and they do prefer a soil which doesn’t get dusty-dry. They will be far better in a soil – I’d like to say – moisture-retentive but well drained – mythical conditions! But they don’t want to be in a very sandy soil that’s dry all the time, they’re much better in a humus-rich soil that will retain some moisture without getting water-logged – they don’t enjoy boggy conditions, it’s very true. Once they’re established in that sort of conditions, they like to be well fed – they’re quite hungry feeders. So either make sure that you incorporate some well-rotted manure into the soil before you plant, or you can mulch with well-rotted farmyard manure or you can just continue to liquid feed: any method will do equally well – but get the food down them, basically, they do like regular feeding. Then they’ll provide you with plenty of lush colour both in foliage and in flower, right through the summer. But if we’re keeping an eye on them, because there are some varieties that have got viral infections in the foliage – if you get this sort of mottling, patterning on the foliage – it can mean that you’ve got a virus, it’s worth keeping an eye on them. It’s particularly disfiguring in the variegated varieties, so do keep an eye on them, it’s well worth watching out for that.
Now with the hardy varieties, probably the best one is Canna iridiflora eckmanii. This one really does look like a Banana growing outdoors – it’s a wonderful, great thug of a plant. I got my first snip of it from the head gardener at Lanhydrock, who very kindly dug me up a piece. Mine grows regularly to six foot in the garden. But it is hardy. Having said that, it needs protection to overwinter properly because unfortunately it won’t actually get going in the spring, very often it’s so slow because of the cold winters or wet winters or whatever it might be which stop them from getting kick-started early enough: quite often it’s September or October and we’re almost heading for the first frost before it actually starts flowering! So what I’ve done with mine is that I usually lift half of it, leaving half of it in the ground, and put it in a pot in the greenhouse just to get it off to an earlier start – it’s only a cold greenhouse, there’s no heat protection – but it gives them a bit of an earlier start, you can get them planted, and if you get them out early enough and growing well, usually you would expect to have flowers from the second half of July and then it will carry on flowering right through until the end of the autumn. But the difference with that one is that the flowers hang: you have a spike of flowers growing up but the flowers on it hang down, whereas with the traditional Cannas they stand up like a Gladioli.
The non-hardy varieties and the hybrids need to be wintered indoors in a frost-free greenhouse or polytunnel which suits them well. While I say ‘frost-free’, in all honesty, as long as we keep them on the dry side, they’ll take a degree or two of frost, but if they’re soaking wet and frozen cold then they’re not going to be happy bunnies. So if you can give them that little bit of protection, it’s surprising what you’ll get away with. And then in the spring, if you’ve lifted them and put them into trays, lift them out of the trays, put them into nice big pots with fresh compost, get them off to a good start, ready to plant out again in the summer. Hardy varieties can stay outside in winter: as I say, I divide mine in half as an insurance policy, put half in a cold greenhouse (a) because it starts off earlier and (b) just in case it’s such an evil and horrible winter that the original plant doesn’t survive.

Cactus, growing out of doors
Q Can I grow Cacti outside in this country, and if so, what soil do they like?

A. Cacti outdoors in this country are in all fairness a non-starter. It's not the cold that does for them as in their native climes they withstand sub-zero temperatures: it's the rain that kills them over here. So the only way you could grow them out of doors would be with some sort of cover to keep the rain off. As a rider, I would suggest succulents such as Agaves and Aloes if you want to create that look with slightly fewer vicious spines. Any soil for Cacti must be free-draining. From the salt point of view, they are actually quite tolerant but drainage is the key issue.

Callistemon, becoming 'leggy'
Q. I have a Callistemon which is about four feet high. Is it normal for it to lose all its lower leaves?

A.Yes, I’m afraid this is just something that Callistemon do! People buy a Callistemon and then are rather disappointed that it loses its lower leaves and acquires the ‘bare bottom’ look. And if you attempt to cut it back to the old wood, it doesn’t like it. I would suggest that as soon as it’s finished flowering this year, you look at giving it a haircut – a gentle haircut, don’t go back into old wood, but enough to encourage some more new growth to fill out and, hopefully to cover up, that bare bottom. But it is a natural consequence and it’s not something that you’re going to be able to completely get rid of. Cutting it back, keeping it fed and well-mulched so that it doesn’t get too dry (despite the fact that it will cope with very dry conditions), all of those things will help it to hold its foliage at the base as long as possible

Camellias, how to choose early-flowering varieties
Q. Can you suggest really early varieties of Camellias – the ones that are in flower now (January)?

The very early ones are the sasanqua varieties which are the winter-flowering Camellias; they really started flowering before Christmas. Ones like ‘Narumigata’ which is a lovely pink-and-white stripey one, and ‘Rainbow’ are beautiful. ‘Hugh Evans’ is another good variety with a gorgeous perfume on it. The sasanquas do have quite a nice perfume with them, unlike the spring-flowering Camellias – the williamsii and the japonicas. Of the main-stream Camellias that are starting to flower now, the williamsii that come out first generally the single ones will be first out in the rush, like ‘Cornish Snow’, ‘St Ewe’ and ‘Bow Bells’ – they’ll be the first ones showing their colours. But be careful with the very early ones, because if we do get a hard frost, it’s inevitable unfortunately that the flowers will get clobbered! If you’ve got a Camellia that looks like it’s got the potential to get straggly, don’t be afraid to give it a haircut immediately after flowering. Last week I was in Italy on a plant-buying trip, and they had plants down there to die for – including standard- and pyramid-clipped Camellias: they’ll clip anything that stands still for long enough! But really so full of buds and yet they were clipped into pyramids. So, prune them back immediately after flowering and you can keep a much denser, bushier plant.

Camellias, how to grow
Q. Can you tell me how to start growing Camellias, and the best early varieties?

A. Camellias are probably one of the easiest plants to grow. You’ve got two main options: you can grow them in the ground, you can grow them in a container. Obviously, if you’re going to grow them in the ground then they would need to be in an acid soil. Particularly in Cornwall and in parts of Devon, we have mostly acid soil, but if you’re not sure, do do a soil test before you plant them. Having said that, they make superb container plants and again, if you’re in a limey, hard water area then just collect your rainwater and water them with that, rather than with tap water. They should be quite happy, you shouldn’t really have an issue with this. If you’re going to grow them in containers, make sure that you do pot them up in ericaceous compost though as they will require an acid compost to do nicely. They are plants that are best grown in shade or sunny-shade because they don’t enjoy getting baked in the summer. They’re happy in some sun, but not to get absolutely cooked by it. The only other positioning factor that normally concerns them is, it’s best to avoid the morning sun: it’s not that the plant itself is affected by it, it’s that if the flowers have got frost on them in the winter, the morning sun de-frosts them very quickly and they’ll then spoil. So, it’s sort of an old wives’ tale but it’s there for a practical reason, so try to avoid the morning sun for them. Afternoon or evening sun, no hassle at all.
As for variety, the sky’s the limit. There are so many lovely varieties and they’re already starting to flower, particularly down here I’ve seen loads of them out. ‘Bow Bells’ is probably one of the prettiest early ones, along with ‘St Ewe’: both of them are single. C. japonica ‘Little Bit’ is already out in flower. A lot of the ‘Williamsii’ varieties are generally the earlier ones, whereas the japonica varieties tend to be in the second tranche of flowering. But that’s not always true, there is quite a big overlap. But the very, very early ones are the ‘Sasanqua’ varieties which are the winter-flowering Camellias: some people call them autumn-flowering because they usually start flowering before Christmas and a lot of them are quite sweetly-scented as well. If you wanted some very, very early, say around Christmas time - December and January - then they’re ones that are well-worth looking out for – ‘Nurumigata’ and ‘Jean May’ are two particularly nice ones, but ‘Burgundy’ is also very pretty. But there are, literally, hundreds and hundreds of varieties: we’ve got about a hundred-and-fifty varieties in our nursery at the moment, working up to a range of about four hundred which we’re hoping to aim for in the next couple of years. And they’re all so collectable and gorgeous. But I suppose that, if I had to pick two favourites I would go for ‘EG Waterhouse’ and ‘Margaret Davis’ – and I’d probably have a third runner-up of ‘Desire’. But they’re all such wonderful, wonderful plants.
As for diseases, unfortunately Camellias are susceptible to Phythophthera remorum, which is the Remorum Blight or Sudden Oak Death and they’re one of the notifiable plant groups which are susceptible to it. But in most people’s gardens, even in areas where Remorum has become a problem, I’ve never yet found it in a private person’s small garden. It’s in private, big gardens, i.e. in gardens that open up to the public and gardens that are acres and acres – it has been found in some of those – but generally it’s come in on something like Rhododendron ponticum, or come from another source. Because they have such a big, thick, waxy, leathery leaf it seems to take them quite a while to get an infection. And even if you do get Remorum Blight and the plant dies (it will eventually kill it), the chances are you won’t infect anything else unless you’ve got nothing but Camellias in your garden, because it’ll die, you’ll notice it’s died, you’ll get it out of the garden, you’ll clean up all the dead leaves and it will have gone anyway. Tthat is the best method for getting rid of the problem. So that’s the main disease that affects them. They are also affected by something called Bud Blast, that’s when the buds fall in spring: before they open they go brown and drop off. It’s a disease that’s been around in Camellias for a long time and the way to prevent it from recurring on your plant is – when the flowers fall off, a really good hygiene policy is to pick up every flower, every petal, from around the plant and get rid of them. Don’t compost them. Any fallen leaves – get rid of them, because what will happen is that any buds with Bud Blast that drop off will harbour the spores and they will bounce back up on to the plant again if they’re left there. So good hygiene will keep that under control and it shouldn’t be a problem. Other than that, they are very tolerant, very easy plants: all they require is a bit of food, a bit of water and a bit of TLC.

How to propagate Camellias
Q. How do you propagate Camellias?

Traditionally, Camellias are propagated by cuttings, and I suppose in fairness most people have best success using traditional heel cuttings. To do that you would need to do semi-ripe wood cuttings which are usually done around the end of June or July time, when you’ve got a reasonable amount of growth on there – the bit you’re looking for is between where it’s brown and where it’s green – that’s the semi-ripe bit. If you’re going to do a heel cutting then you need to pull a little side-shoot down off the main stem. Trim the heel back, trim off the bottom pairs of leaves, stick it in rooting powder, pop it into some well-drained compost – and off you go!
But you can also put them into the ground, if you want to. You need to prepare a bit of soil, ideally somewhere that’s semi-shadey, somewhere that you can keep watered and which is a bit sheltered. Generally, you would dig a trench: very often people cover the bottom of the trench with sand or coarse grit. Do your cuttings exactly the same way I’ve described, put them against the side, backfill it with soil, give it a good drink and walk away. You’d be looking about 12 months for those ones I suppose to root: Camellias are fairly slow rooting. If you do them in a propagator, you’re still looking at six months for rooting, if not longer: but in the ground you’re talking of about 12 months.
A fun way you can propagate Camellias, if it’s a biggish bush you want to do, is to take air cuttings. To do this you need to get some Sphagnum moss, which you can buy in local centres. Try and buy some environmentally friendly moss if you can, not something that’s been dragged half way round the world – you can buy it from licensed sources, so try to make sure you’ve got some of that. You want to make an incision into the stem – not a huge stem, you’re looking at doing this with af side shoot again – what you need to do is to cut more or less halfway through the stem but not all the way through. You pack the Sphagnum moss around with a little bit inbetween the gap that you’ve cut: then you wrap the whole thing up in Clingfilm or some form of plastic, sealing it above and below the cut. You’re making a lump of moss about the size of your fist around this cut – wrap the whole thing up in plastic, make sure it’s nice and moist in there, and walk away. Hopefully, the Camellia will root into the Sphagnum moss, but of course it’s still got its umbilical cord to the parent plant. So it’s rather like layering a rose under ground but you’re doing it up in the air. Apart from the fact it’ll look as if your Camellias has got some rather strange growths, it’s quite a nice way of propagating them! So you’ve got all these methods for vegetative propagation.
Of course, on top of all that, if you really fancy a giggle, try doing them from seed. That’s somewhat more hit-and-miss, there’s no guarantee what the results are going be, but if your Camellia does set a great big, fat, juicy seed pod, try sowing some Camellia seed. They will probably need stratifying, which basically means beating them up with some grit first and then stuffing them in the fridge for a few weeks until they’ve been cold-treated. Take them out, sow them in a propagator and wait and see what pops up! But bear in mind you’re going to be waiting a few years to see what the flowers are like. There are species Camellias but there aren’t many of them around: I’ve got to be fair and say that for my money they’re for the purists. Really the best ones nowadays that you’re looking at are the hybrids now – and they are superb.
Probably the one that people like to grow at the moment is Camellia sinensis – for those who like to grow their own green tea and like following in Tregothnan’s footsteps. It’s quite a sweet little bush with a very small white flower – but don’t plan to be picking enough tea to be starting up your own production unless you’ve got an awful lot of acres to spare!

Cannas, how to overwinter
Q. How do I overwinter Cannas?

A.Cannas are best overwintered in a small greenhouse or conservatory without too much heat which could precipitate premature growth. I prefer to wait until the first frosts have killed off the foliage before bringing them in. They can then be overwintered in very much the same way as you would Dahlia tubers, but keep them in the posts of compost and don’t allow them to dry out completely. Then in about February, knock them out of their pots, shake off the old soil as far as is sensible, and re-pot them into fresh compost. Give them a good drink to initiate growth and they should be on their way. When you do re-port them in the spring this is a good time to do any dividing and get some babies for free.

Carrots, last time to sow
Q. When is the latest time to plant carrots?

A.The end of September would probably be the limit. You will almost certainly get smaller crop production and they will take longer to mature, but should be none the worse for that. Normally, August would be the latest month to sow carrots, with the maincrop in June.

Cats, keeping them off seedbeds
Q. How can I stop other people's cats from ruining my seedbeds?

A. This is a perennial problem for gardeners and the solutions are varied. Firstly, remember that cats are highly sensitive to smell, so anything that marks or detracts from the remains of their previous spoors will help to discourage them. One of the best things is to get a bar of the cheapest whiffiest soap you can find and grate it up. Unfortunately at this point you have to clear up any cat mess that has been left before you sprinkle the grated soap over the area you wish to protect. Another simple method is to push short canes into the ground at 6-9 inch intervals and then weave cotton betwixt and between them to make a convoluted grid. There are more expensive options on the market such as water sprinklers with motion detectors. Or one of the most novel approaches I have seen is a small plastic frog which croaks when you approach it. If your cat has a nervous disposition, it will soon go elsewhere.

Coronilla emerus
Q. I have a Coronilla emerus. Nobody seems to know much about it, although it's mentioned in a book 'The Seaside Gardener' as having been grown since the 16th century.

A. Coronilla emerus certainly isn't the best known of the Coronilla family, and in my view is not the showiest of the family, although it is a pretty plant. I would recommend Coronilla glauca or C. glauca "Valentina", which flowers very freely and smells deliciously of coconut.

Carrot Root Fly
Q. What is the best way of protecting carrots from Carrot Root Fly?

A. The best protection is the barrier method! Carrot root fly are afraid of heights and rarely fly higher than two to three feet off the ground. So a simple method would be to press bamboo canes into the ground and drape horticultural fleece over them, thus preventing access.

Caterpillars on brassicas
Q. Every year caterpillars eat my brassicas to bits. What can I do about it?

A. Cabbage White butterflies? - you have two choices. Either spray with a contact insecticide which is safe to use on edible crops, or a more satisfying, but more time-consuming, method is to pick them off by hand and squash them!

Children and gardening
Q. How can we get our small children interested in gardening?

A. As soon as they're able to take an interest in any topic, is the time to start. There are some fabulous garden tools and accessories on the market for children, as well as garden starter kits which will help to foster their interest. Depending on the age of your child you could consider persuading your local junior school to start a gardening club. It is important to encourage respect for plants at an early age if we are ever going to combat rising vandalism.

Chili Peppers, using collected seed
Q. If I sow seeds out of Chili Peppers, will they breed true?

A. As with all seed taken from any fruit or veg you buy in a shop, there is always the chance that it has cross-pollinated with something else. So there's no harm in trying your seeds but don't blame me if you get some interesting results!

 

Christmas presents, books for
Q. Can you recommend some books to give as Christmas presents?

A. For most gardeners, Christmas can be a time of torture because they feel trapped in the house and they can’t get out. So, give them their own little escape valve and buy them a lovely, lush gardening book. Even if it looks like a coffee-table book, there’ll be ideas in there and things in there which make most gardeners start to go all slobbery about the chops! Even just a new, up-to-date Plantfinder is very often a very welcome gift to receive. But there are some beautiful books out there now and at some very attractive prices. So you can reward the gardener in your life with a good range of books, ranging from ‘Fifty Ways to Kill a Slug’ which I think is a very fun book and particularly if the gardener you know gets very frustrated by slug damage; through to some beautiful design books, books on plant association, recycling in the garden, how to make different ornaments, how to use natural willow in the garden, down to the ordinary plant encyclopaedia type of books, which inevitably – it doesn’t matter how many books you look at – you will always find new plants you haven’t seen before. The big RHS dictionary is a very good buy, as is the Readers Digest, the Hilliers Illustrated Manual is an invaluable resource. There’s a wide range of specialist books on individual topics, and again if you know that somebody is very keen on a particular group of plants, sometimes it’s nice to buy them a book dealing with that particular topic, whether it’s Magnolias or Fritillaries or Irises or Dragonflies – whatever 'pops their candle' !

Christmas outing
Q. Please can you suggest an original kind of Christmas present?

A. Something which can stretch to any budget for a gardener is to arrange a day out, and it sometimes is quite nice to choose a garden that the gardener in question hasn’t been to before and arrange for a ‘mystery day out’, to take them out for a day to visit the garden – or maybe make it two gardens. The fee can be as outrageous as the budget will allow, but gardeners like nothing more than to arrange a nice day out, having a look at what other people have got, and gleaning ideas, and it makes a lovely and relaxing present – in fact I’d like somebody to buy me one! One of those opportunities where you can make up your own present – you can make it into a little voucher and say ‘it’s to be redeemed at your pleasure’.

Christmas plantings of trees
Q. Can you suggest trees to give for planting at Christmas?

A. If you’re still looking for a last-minute Christmas present for the gardener in your life, there are quite a lot of things that you could look out for. Probably I wouldn’t suggest a houseplant at the moment, because your house is probably stuffed to the gunwales with Christmas Trees, decorations, cards and everything else. So maybe it would be quite a nice idea to give them a reason for actually going out in the garden on Christmas Day. So why not give them a tree to commemorate Christmas? Personally, I’d like to plant a tree every Christmas Day, and this year I’m hoping to plant an Elm tree of a newish variety which has come to us from France, which has for twenty years been grown in an area where there is known Dutch Elm Disease and has shown 100% resistance. So we’re hoping to help introduce it to this country more widely: it’s called Ulmus lutèce which looks very much like our native Elm which is virtually extinct, tragically. It would be great to see them coming back into our landscape again. So we’re hoping to plant a small group of them in our field this year, weather permitting, on Christmas Day.

Christmas presents,useful tools for
Q. Have you any suggestions for practical Christmas presents?

A. If you're stuck for a present for the gardener in your life, you’ve got several choices of direction. This week, we’ll look at practical presents. Depending on your budget, I’ve yet to find a gardener who would not appreciate a good stainless steel spade (or spade and fork), all nice and shiny with a big red ribbon on. Bear in mind, if you’re buying for a lady gardener, I personally find a border spade and fork better, and if your garden is very small, a border fork and spade fit in amongst the other plants more easily. But the guys like the big ones: I think it would be better if I don’t comment any further!

Christmas Trees to keep
Q. For people who want to choose a rooted Christmas Tree to grow on outside, and who find it a bit depressing to throw out a tree each year, is there a tree or a substitute Spruce that will grow on?

If you don’t like the idea of buying a Christmas Tree that has to be thrown away at the end of the Christmas period, be careful if you are tempted by the idea of buying a ‘rooted’ Christmas Tree. If it’s a large one, over four foot and rooted, it will have been dug up, it will be very roughly rooted and unlikely to have a root ball – its chances of survival are not high, although many people do get them to grow if they keep them moist and keep them indoors for the shortest possible time.

But if you want to have a plant to use as a Christmas Tree, and keep it outdoors for the rest of the year, there are quite a few varieties you can go for. Now, if you wanted to be traditionally English, you would in fact go back to a Holly – you could grow it in a pot and bring it indoors for the Twelve Days of Christmas, but keep it indoors for the minimum length of time, and also don’t stick it next to a roaring fire or central heating radiator. It needs to be kept in a cool room, and moist while it’s indoors. If you want to go for a traditional conifer type, it doesn’t really matter what variety you go for, you want to go to your local centre and have a look at the ones that are pot-grown – and be careful that they are in fact pot-grown and not dug up and stuck in a pot. There is a difference and the ones that are just stuck in a pot again may well just be rough-rooted and may not be guaranteed for survival so check when you buy one, if the company happily guarantee the plant, you can be fairly sure that it’s been grown to live and not just dug for Christmas. And then it’s down to personal preference really, what variety you want to go for. ‘Non-drop’ Christmas Trees are all popular – the Abies nordmaniana and Abies procera always make good Christmas Trees, but the Picea abies is the traditional Norway Spruce that so many of us use – a prickly little beggar but makes a lovely smell in the house. There is also Abies koreana, very slow growing but with lovely blue cones on them when they get more mature, which people quite like to use. Pinus contorta which is in fact a traditional Christmas Tree used in Scotland, is a popular choice as well, but it does tend to grow rather quickly and leggy: probably difficult to grow a good one in a pot if you wanted to use it for Christmas. The choice is very, very personal.

Cistus ladanifer, going leggy
W. I have some Cistus ladanifer which have become very leggy. Should I cut them back to make them bushier?

A. Cistus don’t like being cut back hard: they’re far better cut back regularly as a young plant to stop them reaching the point of becoming very leggy. Cistus ladanifer is a relatively tall variety and once it becomes leggy you’ve got two options: one is to wave goodbye to it and the other one is to plant something in front of it to cover up the legginess. Obviously this will depend on the situation where you’ve got it and which you decide you want to do with it. But cutting it back hard to encourage new growth unfortunately is a non-starter with Cistus.

Citrus fruit, how to grow
Q. How do you grow Citrus fruit?

Citrus are actually remarkably easy plants if you bear in mind where they normally grow, which is on poor, mountain soil in Mediterranean countries. This give you an indication of what they really would benefit from in terms of growing conditions over here. It basically means that they need to be kept dry, and that is the main reason why they’re overwintered under glass in this country, because we don’t do ‘dry’ in the winter over here! – much as I wish we did. So ideally your Citrus want to be outdoors during the summer, so I would normally say from the end of April or beginning of May until October. Put them outdoors on a sunny patio, somewhere where they’ll get the best of the sunlight and if we’re suffering from torrential downpours you can pull them back against the house and protect them from the worst of the rain. They will benefit from being outdoors during the summer and once autumn sets in, wheel them indoors again. Cold greenhouse, cold conservatory, or pamper them in a heated one if you wish to but they’ll grow just as well in a cold one but you won’t get them into flower quite so early if they’re in a cold greenhouse or cold conservatory.
Feeding for Citrus is pretty easy if you follow two basic rules: from September to March you use ‘Winter’ feed and from April until September you use ‘Summer’ feed. It’s that simple! They like to be fed, you do need to have the two different nutrient make-ups because in winter they’re not actively growing but they tend to be putting on flowerbuds, so make sure that you have the two different nutrient feeds for them. And, critically, in the winter, again because of where they are, if it’s a cold greenhouse or conservatory, do not over-water them – they don’t like to be excessively wet at the roots during their more dormant period. So keep an eye on them.
Now from the point of view of pests and diseases, the biggest culprit is usually mealybug or woolly aphid, and you’ll get that in the crooks and nannies inbetween the stems. The other really bad news is scale, like little round discs on the underside of the leaves: if you squidge them you get a goo out from them which is the insect. They are notoriously difficult to get rid of. If it’s a small infestation, cheap alcohol (one of the ones you don’t mind wasting half a teaspoon of), put it into a teacup, get a cottonwool bud, dip it in and then dab it on to the insects: that works for mealybug, woolly aphid and scale. It doesn’t make them drunk, it dehydrates them, so they don’t have a happy ending. But you can obviously get proprietory sprays, but with scale and with woolly aphid particularly, contact sprays don’t work, so I’d normally recommend that you get a systemic insecticide for those ones which is specific for those particular pests. Not the easiest of things in the world to get rid of, and persistence will be required but it’s well worth making the effort because otherwise you’ll get a serious infestation which is quite unpleasant. You can use biological control, especially if you’ve got them indoors and the infestation is in the winter, but obviously when you put them back outdoors, the biological control isn’t always successful unfortunately. As far as compost and potting up is concerned, always use a John Innes based compost for Citrus, they much prefer it. Don’t over-pot, try to pot up a little and often, so just go to one size bigger pot each time: sometimes they’ll be happy in there for a couple of years, sometimes just the one year, but just keep it ticking on, as I say, a little and often with those ones. Simple instructions, and then you’ll have a very happy Citrus.

Climbers for a seaside garden
Q. Please can you suggest some flowering creepers which are suitable for a coastal garden?

A. Some of them are common climbers like Honeysuckles, Russian Vine, roses, Hydrangea petiolaris, Wisteria solanum (which is the Potato Vine). Climbers benefit from the protection they are climbing over, which reduces the wind damage.

Climber for south-facing wall
A. Climbers would include the Honeysuckles and a fair proportion of Clematis. If you want to go for something more unusual you could consider Actinidia kolomikta, Schisandra and Campsis.

Climber for a south-west wall
Q. Please can you suggest a climber for a south-west wall?

A south-west facing wall has probably got be one of the easiest positions to cover. Most climbers would really enjoy this sort of a situation, so – almost – the sky’s the limit. A south-west facing wall – even on the coast - is quite a precious position, so don’t squander it on something too common! I would consider looking at something really out-of-the-ordinary. A few choices would include Fremontodendron ‘Californian Glory’, with wonderful, big, golden-yellow waxed cups – it’s actually a wall shrub, I suppose, rather than a climber and it has almost a figleaf-shaped leaf. If you have a skin allergy, though, be careful if you handle it, because the indumentum on the underside of the leaf comes off and it itches like merry hell on your skin and can cause irritation problems. But it is a beautiful climber: if you see it in full flower, it’s really, really striking. Another real favourite for me would certainly be Cytisus battandieri, the Pineapple Broom, partly because pineapple is my favourite fruit in the whole wide world and anything that smells or tastes of it has got to be a very good choice. Again, it’s a wall shrub: it’s got a leaf that’s very unlike normal broom in that it’s a soft, rounded leaf with very fine, grey hairs on it and like most plants that have a greyish foliage, it's very good on the coast. The flower spikes are probably nearly five or six inches tall. The individual flowers are true broom flowers, but they stand up like a little flat cone: it smells of pineapple, delicious. On a south-west facing wall it would be a gorgeous choice.
If you wanted to go for a combination planting in that position, you could think about a climbing rose, maybe with a clematis growing up through it, which would look really good. You might think about something like ‘Dublin Bay’ which is a wonderfully rich, crimson velvet-coloured rose. Through that you might possibly consider growing a clematis like ‘Nellie Moser’ or ‘Bees Jubilee’ which are beautiful soft lilac with a deep stripe in the centre of the flower, which will look really good together. Or you might go for a gold combination and possibly think about Rosa ‘Golden Showers’: I might consider putting something like Clematis Jackmanii ‘superba’ which is a dark purple clematis through it. Either of those would make a good combination. One other thing I might possibly toy with growing in a position like that would be a Campsis. Also known as Bignonias, they have lovely trumpet-like flowers and they need to be grown on a hot wall so that the wood will ripen properly andt form the flowers: it is relatively free-flowering in that position. They flower in the late summer, and if you get one when it’s fully in flower it’s really striking, really splendid.

Colourful foliage
Q. Please can you suggest some colourful foliage for all-the-year-round effect?

A. This is a huge section, but some of my favourites which suit most conditions include Photinia "Robin" which gives young red growth for virtually twelve months of the year, Aucubas (commonly called the Spotted Laurel), these are a much maligned group which thrive in poor, shady conditions, bringing a flash of light to otherwise drab areas. All the evergreen Euonymus, which range from groundcover to substantial bushes, are generally best known for their flamboyant spring colour. If you choose one of the variegated varieties "Flaming Silver" this will give you the best of both worlds. If you do have a garden in a milder area, have a look at the Coprosmas which come in a lovely range of coloured foliage which is also deeply glossy. And that's just for starters!

Comfrey, breeding true
Q. If I sow seeds from my Comfrey plants, will they breed true?

A. With Comfrey, it will depend on the variety. If it’s Symphytum officinale, which is the straight species, then it will come true from seed because that is a straight species, there’s nothing to go back from, if you like. If it’s a selected form, one of the named varieties like one of the ‘atlanticum’ varieties may be, then that will not come true from seed and again you may get variations on a form. But Symphytum, even with the named varieties, are not heavily hybridised, so even if they take a step back down the evolutionary chain, you’re not going to find a dramatic variation from the original plant with those ones. They’ll also propapagate so easily from runners: you can break pieces of them and pop them in the ground and within a couple of weeks you’ll have a fresh baby rooted and raring to go. So Symphytum is one of those plants that’s dead easy to propagate. And of course Comfrey’s a brilliant thing for a green manure crop – either put it straight into your compost or make a fairly disgusting brew by putting it into water.

Comfrey, when to move
Q. When can I move some Comfrey plants? Can I divide them, too?

Now is probably as good a time to do it as any, and probably about as late as you’ll get away with. If you’re going to move the clump intact: dig around, lift it up, dig a new site, pop it in, fill the hole back in, give it a really good soak and it probably won’t even bat an eyelid! If you want to divide it, which you’d probably still get away with now: you want to lift the clump and put two forks back-to-back within the clump and push the handles together and that should split the clump quite nicely – or you can just chop it through with a spade. Get the holes prepared, fill them with water and let it soak away. Then put the clumps in there, backfill them with soil and they’ll be fine. I’m not going to say that Comfrey is un-killable, but it’s close! It’s a very well-behaved and tolerant herb.

Companion planting
Q. Please can you suggest some companion planting for a vegetable patch?

Companion planting was used for many years as a natural method of pest control, both in the garden and in the vegetable garden, but became less popular with the easy availability of pesticides which made control of insects easier – or so people thought. But with the resurgence of organic gardening, people have been much more conscious of whaqt they are eating, companion planting is gaining in popularity once more. I agree a fairly obvious example are planting things like Marigolds next to carrots, because the smell of the Marigold is very strong and will override the smell of the carrot. Usually, French Marigolds are used, not English Marigolds. If you think of the very smell, whiffy Marigolds that you use for bedding – the smellier the better, basically. Tagetes will work as well in that sort of a situation. The Marigold family are probably one of the most popular plants that are used for companion planting, because of the overriding smell which masks the smell of the plant you are trying to protect. Other companion plants form almost a symbiotic relationship with the plant that you’re growing intentionally, i.e. the vegetable and the companion plant you put in, because sometimes a chemical will be released which will, again, normally fend off insects. Virtually all companion planting revolves around disguising the crop you’re growing from the predatory insect. I can’t think of any examples of companion planting that are done for disease purposes in the form of a fungicide: most of them in fact are just for pesticide control. But you can use things like Marigolds near the base of Runner Beans, they work quite nicely to disguise the smell. But when you look at some form of non-chemical gardening – I am always cautious of the use of the word ‘organic’ because I’m not sure actually of the true meaning – in non-chemical gardening there are a lot of other things, along with companion planting, that you can use to cut out chemicals from the garden, whether it’s something like the barrier method, again for carrots, where you put a small screen around them – Carrot Root Fly, believe it or not, are afraid of heights and don’t fly over eighteen inches above ground, so a little two-foot roll of fleece around your carrots will protect them. Simple tricks like that do go a long way to helping the plant.

Compost for succulents
Q. What sort of compost should I use for starting and maintaining cuttings of small succulents for rockeries?

Most rockery plants and certainly most succulents do better if they’re in a relatively low feed compost. They prefer to be in a loam-based compost, so I would normally recommend a John Innes No 1 for rooting – but do make sure you work some extra grit in with them, because they really do need to have very good drainage to do well. Alternatively, you could try rooting them in a Coir compost: we have found that we can be very successful with most species of plants, ranging from Camellias right through to succulents. It’s a very versatile medium because it’s free-draining, which allows you to add as much water as you need without encouraging the plants to get rotted. So either of those two would do particularly well.

Compost, how to make
Q. Please can you tell me how to make good compost?

A. This is always the 64-million-dollar question, and you will get almost as many answers as there are gardeners. However, my own recommendations are usually to make your own compost bin out of timber. The basic construction should give you three fixed sides with timber fixed in such a way as to allow approx one-inch gap between the boards or if you are using a single sheet, drill half-inch holes approximately every six inches. The fourth side should have the same properties but be removable for easy access to your compost. I usually recommend that you aim for a one-metre cube.
So much for the physical container, the important bit is the stuffing! The key to good compost is layering. You will almost certainly kill your compost heap if you put in more than three to four inches of grass clippings without putting a ore open layer of material inbetween, which will allow the air free access. My husband prefers to allow the grass cuttings to dry out for a day or two before putting them ion the heap, but opinions vary on this.
One of the other most important aspects of getting a good compost heap going is an activator. Now traditionally, male gardeners have easier access to a free and very effective activator, which is human urine. Of course there’s nothing to stop the ladies from doing the same, it’s just that the application is a little more tricky. If this doesn’t appeal (and don’t be put off by reasons of supposed hygiene, as uric acid breaks down very quickly), then you can buy proprietary activators such as Garotta or Ammonium Sulphate. This should be watered on as all composts need some moisture.
Finally, a square of old carpet should be put on top of your last layer and lifted off as you add more to the heap. I prefer to put a waterproof sheet over the whole lot. Once you have filled your compost bunker and tucked it up nice and warm, leave it for approximately four weeks, then open it up and turn your compost out either on to a sheet of plastic or into a second bunker next door, aiming to put the newer material from the top to the bottom of the next bunker. This can be repeated two or three times until the compost has reached a level of decay to your satisfaction. One final tip, when you empty your compost bunker to use, leave approximately six inches in the bottom of the bunker to act as a starter for your next heap. I never said it was easy!

Cordylines in polytunnel
Q. I have some Cordylines in pots in a polytunnel. Some of them have a layer of Vermiculite spread over the surface of the compost and these plants are looking very yellow. Any suggestions?

A. Cordylines are hungry feeders and will respond to almost any fertiliser but I would probably recommend a soluble balanced feed, something like Miracle-Gro. Feeding a little and often will produce good results. I think the Vermiculite is irrelevant to the issue.

Cordyline growing next to house
Q.I have a 15 foot (at least) Cordyline australis growing six feet from my bow window. Is it a threat to the house foundations – and could it be moved?

A. The answer is: not a cat-in-hell’s chance, no. It will not move and survive! It’ll move, yes, but in ‘kit form’! But the chances of it actually doing structural damage to your house, unless you are on heavy clay soil, are slim to negligible. So, unless your reasons for wanting to move it are for reasons of light, personally I would leave it where it is.

Cordyline, rotting at centre

Q. Some of my Cordylines are rotting at the centre. Will they shoot again?

A. No, the honest answer is, they won’t shoot again. Also, Cordylines are susceptible to a disease: we don’t really know what it is, but they are dying. We think it’s a form of Phytophthera, but what’s happening is the tops are dying and the stems are going all rotten and soggy in the middle. Even if we cut them back, they’re not re-shooting, so in all honesty I would say, if it’s gone rotten and soggy in the middle, if it’s this that’s caused it – then it won’t shoot again. You’ve got two chances: you can chop it back down to ground level and it has two options – it can shoot or not shoot, you haven’t lost anything.

Cordylines, yellow marks on
Q. I have a number of Cordyline palms in pots. Every winter their leaves develop yellow blotches, although in spring the new growth is a healthy green. Could you tell me what causes these yellow markings and suggest how I can prevent it happening?

A. It's difficult to pinpoint the precise cause of yellow spotting, but generally it affects Cordylines that seem to be a little too wet at the roots. As long as the young growth comes through fine, then don't worry about it.

Corylopsis, moving

Q. I live on the Oregon coast, about three miles from the ocean. We have strong north winds in the summer. My garden is bounded on the east by a two story building, on the north by a six foot fence, on the east by another one story building and some Hydrangea, Birch trees and Myrtle, a Spruce. And the south is a picket fence with gate. last spring I planted a three foot diameter Winter Hazel (Corylopsis) in front of the north fence, where most of the sun is during mid day. When the wind really blows, it tends to eddy around in the garden and there isn't much protection anywhere. I am contemplating moving the Corylopsis near to the south gate, between the Hydrangea and under Birch trees. It will get less sun. I'm unsure whether transplanting would be a good thing for it. It feels like a more protected place but it probably will get some wind there, too. and I'm not sure when is the right time to transplant. It is very cold these days, and I wonder whether transplanting during cold weather is good for the roots. Any advice? Thanks so much.

A. You sound as though you have an interesting garden and are not afraid to try some different plants. However, in the case of your Corylopsis, you have chosen a slightly tricky subject. It will certainly resent being moved in the depths of your cold weather and I would recommend waiting until you get a mild period during the winter to move it. However, in the mean time it would probably be a good idea to root prune it in preparation for the move. Go around the plant, just inside the canopy edge of the plant itself, with a spade and cut straight down. Do nothing else but this will sever the roots ready for the move. Corylopsis prefer a more sheltered site, semi shade is fine but they enjoy a hot autumn to ripen the wood and ensure a good flower display. If the weather hasn’t offered a suitable window before it flowers, don’t think that you have missed the boat. As long as it has not come into leaf it can still be moved.

Couch Grass, getting rid of
Q. How can I get rid of Couch Grass on my vegetable patch?

A. Couch Grass is one of the gardener’s worst nightmares. If you’re digging the garden over, and you want to do it organically, you have to have X-Ray vision because you need to take every little bit of root up. So if you want to get rid of the Couch Grass, the best way to tackle it is to dig down a fork and just loosen the soil around that area and gently pull the Couch Grass out, follow it back as far as you can, loosening the soil all the time and pull the root away; all the subsequent roots should come away with it. Continually pulling Couch Grass will eventually weaken it, but it is a job of love, you have to keep doing it. But if you’ve got Couch Grass coming up through a favourite plant, it’s the only way to do it because you can’t, obviously, spray indiscriminately with weedkiller.

If you’ve got Couch Grass coming up in an area of kitchen garden which you’re clearing, personally I would spray with a Glyphosate weedkiller while the Couch Grass is still green and growing actively. Let it take it back in because it’s a systemic weedkiller, and hopefully it’ll go down and kill the roots; and then you may find that some small pieces come up subsequently which you can deal with on an individual basis, either by digging them up or by spraying a small area individually. I would probably favour a two-pronged approach – attack it en-masse with weedkiller and then tackle each piece individually by loosening the soil and digging it up, following it back to base. Couch Grass is almost diamond-tipped, it’s a very pointed grass in the rhizome stage, so it can spear its way through anything. It’s a very invasive grass from that point of view and that’s why it just ‘points’ its way through any rooted areas, and you find it coming up through existing plants without any resistance to it at all.

Cruel Plant, what is it?
Q. What can you tell me about the Cruel Plant or Araujia sericifera? I’ve just been given some seeds.

This is a climber: it’s not very often grown. It’s a toss-up between being overrated or quite interesting! I can’t say fairer than that! It’s quite a nice evergreen climber, not very often offered at all. It grows best on a south or south-west facing wall. I wouldn’t say it’s the hardiest of climbers, but if you can get the seeds to germinate, I think it makes a nice climber to use as a foil for other things. So if you’ve got one growing you can grow something like a Clematis up through it as well. I’m trying to remember the colour of the flowers, I’ve got a sneaky suspicion they’re white, but don’t hold me to it. But it is a nice climber, it is well-worth growing. It’s salt tolerant and certainly one that I would be happy about growing in a coastal area – I wouldn’t have any concerns about that.
Ideally you should grow it on a south, south-west, or south-east facing wall. Having said that, it will actually take semi-shade if it’s got warmth, but I wouldn’t put it on a north wall – a shadey south wall would be fine. As for soil, it’s not fussy at all, as long as it’s got good drainage, it won’t take heavy, wet soil. It doesn’t mind acid or alkaline although I wouldn’t say it enjoys an excess in either direction, it’s a remarkably tolerant plant.
As for its name, ‘Cruel Plant’, I have absolutely no idea. I have a feeling that it’s got some spines on it that are hidden. I’ve got a fascination with common names and that’s one I haven’t checked up on yet.

Cultivators, for vegetable patch
Q. I am thinking of buying a mechanical cultivator for my medium-sized vegetable patch. Suggestions, please?

A. For a domestic situation, I would recommend the Mantis Tiller, which is remarkably light, weighing about 20lb. It has a strange array of attachments but as a rotovator it is small enough to use between existing plants but man enough to deal with the vegetable plot. For more information, go to www.mantis-uk.co.uk. If you go to buy a rotovator you really need to try before you buy, because some of them are distinctly unwieldy. They work on the principle of rotating blades under a guard, and most are just variations on that theme. Another word of warning: only use these when wearing protective footwear, as they have no respect for toes.

Cucumber seedlings, yellow-looking
Q. My Cucumber seedlings were grown in a seed compost in a peat pot. The first true leaves are looking a bit yellow, is that normal?

A. The initial sowing in a seed compost, that’s fine. Once they’ve been pricked out, then they should go into a stronger compost. Depending on how old they are, if the first true leaves are looking a bit yellow, it may well just mean that they now need some feed. If they’ve been grown indoors there shouldn’t have been any temperature variation, so that shouldn’t be a huge problem. So I would suggest that some gentle liquid feed will be all that they really need at the moment. Bear in mind that all the Cucurbits like a lot of food and are fairly hungry feeders. But at the moment, gently does it.

Cuttings, taking in early summer
Q. Are there any cuttings I can take at this time of year?

A. Stem cuttings from perennials and softwood cuttings from lots of tender perennials, including Fuchsias and Pelargoniums. Also softwood cuttings of some shrubs - but this is better done with semi-ripe cuttings later in the summer.

Cuttings, taken in late July
Q.Can you suggest tree and shrub cuttings which I can take now?

A. Virtually all shrubs are suitable for cutting material now, as they are best treated as semi-ripe cuttings. Tender perennials such as Fuchsias and Geraniums (Pelargoniums) will provide a wealth of cutting material now and free babies for next year. Heel cuttings are a matter of personal preference, and professionally is not a system we use very often. Most cuttings are better trimmed above the heel and below a leaf joint.

Cyclamen indoors, choosing and caring for them
Q. How do I grow Cyclamen indoors? Which varieties are best, and how do I look after them?

A. Firstly, if you’re going to grow Cyclamen indoors as a houseplant, buy them from a reputable centre. Do not be tempted to buy Cyclamen from outside garages or anywhere they’ve been left outdoors, unless it is a variety that specifically says they will tolerate being outdoors. There are some, such as the ‘Laser’ series and the ‘Miracle’ series, both of which you can actually use for bedding outside if you like, as well as using them as a houseplant. But for most Cyclamen, you can buy a nice fat one in flower, you can buy one with plenty of buds on it: but make sure it’s a good, healthy plant with a nice-looking corm which is just sitting on the surface of the soil. Once you get it home, it likes somewhere that is cool and light – not over-cold or over-hot, no extremes of anything really. And it’s vitally important to water from the bottom upwards, don’t water it from the top of the pot. Stand it in a saucer, let it drink what it wants, then let the excess drain away. Always take off flowers when they’ve finished, trim them back (you can just snap the stalks off but you’ll be left with a bit of stalk then, so personally I would recommend trimming the flower stalk right back down to the base by the rosette, but carefully.

As for compost, they are really un-fussy. Generally, the compost you buy it in would be a commercial compost and would run out of steam within a month of your buying your Cyclamen, so I would probably recommend that you start liquid-feeding it within a month or six weeks of buying your Cyclamen. If you do decide to pot it on, it won’t need doing until after it’s finished flowering, and then an ordinary multi-purpose compost is fine.

Mediterranean Cyprus
Q. The Mediterranean Cypresses – the tall, dark, pencil-shaped Cypresses – can they be grown in Cornwall?

This is a sixty-five thousand dollar question, unfortunately! Cupressus sempervirens is the Italian Pencil Cypress. Yes, it will grow in the UK and yes, it will grow in Cornwall, but what it really loathes, hates and detests are severe wet winters – and what have we just had? – a severe, wet winter. We’ve got them in at the Nursery at the moment, lovely specimen ones which have just come in to us from Italy. Fair enough, they have no problem growing them over there. But if you’re going to grow them over here, then a well-drained, sunny position – coastal garden ideally – would suit them well. They will not tolerate wet, cold, north-facing aspects, where they never really get a chance to dry out, grow out of the damage that’s been done to the root system and hopefully try and survive that, at the same time as they’re trying to grow! So I would not have said that it’s an ideal combination.
They are salt tolerant, but you really need to give them just that little extra bit of protection, that is the honest answer. They just won’t tolerate the rain – they won’t enjoy it. It’s a combination of factors – the cold north wind, the wet and the exposure – it’s just too much for them.

Cytisus battandieri, pruning of
Q. Eight years ago I planted a Cytisus battandieri, about 1m in height, against a west-facing wall of my house. It is now about 2.5m high and rather leggy. Last year it flowered profusely. I would like to know if it is possible to prune it right back to regenerate growth from the base of the plant, as it is bare to about 1.5m.

A. It doesn't enjoy hard pruning. Best method for pruning is to shorten back the wood that had flowers on, immediately after flowering, but don't prune into old wood.

Damping off in young seedlings
Q. How can I avoid or treat damping-off in young seedlings?

A. The best way to prevent your seedlings from damping-off is probably to water them with Murphy's traditional copper fungicide, but make sure you do follow the instructions. But basically water them at each stage, i.e. at seed sowing, at germination and at pricking out. Seed compost must be able to drain freely. Good air circulation is also vital, once germination has taken place. Another traditional cure for damping-off has always been Bordeaux Mixture, but really the best treatment for it is good ventilation, making sure that you are using seedtrays that have been properly washed and sterilised and to use fresh compost – not compost that you’ve had hanging around for a year – before you start sowing your seeds. So, good ventilation and correct watering will do a huge amount to prevent damping-off.

Dasylirion, choosing and caring for
Q. Can you recommend varieties of Dasylirion and suggest how I should care for them?

A. I suppose the most famous Dasylirion is the one that’s grown on the Isles of Scilly at the top of the lovely steps going towards the big statue of Neptune, which I think is probably D. glaucophyllum. But they’re all very handsome plants of the Yucca-style of family. But they always look as if the ends of the leaves have just been very gently shredded which makes them almost slightly fluffy: where a Yucca would spike you, these ones will just give you a rather nasty brushing! They actually feel and look lovely. But they do need to be grown in well-drained situations, very much similar conditions to Yuccas, in all fairness. They’re from the Dracaena family, so they like the same sort of conditions as palms, Yuccas – all those sort of things. They really do not enjoy being anywhere where they get very, very wet in the winter, so if they have high rainfall they must have good drainage. Beyond that, once they’re established they’re relatively good, tough plants, but not something I’d recommend for the top of Dartmoor! They’re definitely something that benefits from a coastal garden. But they’re wind-hardy, salt-hardy, nearly-everything-you-can-throw-at-it hardy. They’re not that good with cold, their natural habitat is Mexico – coastal areas in the top of South America, so they’re not hardy as such which is why they’re good coastal plants because there are so few frosts. They also flower, but don’t wait up for it, as it were, they don’t have a flower as lovely as a Yucca, but they do flower and they are of the same ilk.

Date Palms, slow growing
Q. We have some one-year-old date palms which we grew from stones. They're in three-inch pots and still only 6inches high: they don't seem to grow.

A. They need to be in a protected environment and they are slow to start with. Again, try a weak liquid feed every fortnight. Don't pot them on at this point.

Dierama, best place to grow
Q. What sort of conditions best suit Dierama pulcherrima? I'd like to know the best location in the garden. Does it like damp or well-drained soil, shade or full sun?

A. Dieramas like those mythical conditions of well-drained, moisture-retentive soil. Basically, they're happiest growing in sun in soil that does not get too dry but does not get waterlogged in the winter. Crack that, and you can grow your Dieramas!

Dimorphotheca (Osteospermum), wilting
Q. I see on your website that you have a "plant clinic," but I didn’t see my particular problem addressed. Can someone possibly help me with my Dimorphotheca barberae? I've had it for about a month. It was blooming when I got it, I planted it in a large container after the last bloom had finished—well-drained soil and pot. It's been getting full sun and I was concerned because it seemed to have stopped blooming after the original flowers work gone. This week I found a large bud on it, and was delighted. But yesterday I found the whole plant wilting. I poked in the soil and found it somewhat dry (but not bone-dry), so I gave it good dose of water. Today it's still badly wilted, so I took it out of the pot and examined the root ball. Looks fine. The only notable thing was an earthworm in the pot, but surely he's not doing any harm. I've repotted it and put it out of the sun for the time being.

A. It looks to me from your photographs as if it has been over-potted and over-watered. Looking at it, I think the answer is that it has been put into quite a big pot, quite early on. Despite the fact that you’ve had it on a sunny, warm patio, I think it’s just gone into too big a pot too quickly. Sometimes (not always) they can go downhill when that happens. The way it’s collapsed strikes me that the problem is at the root. If I were you I would knock it out of the pot and go down a size in pot – ‘unpot’ it, I suppose, rather than ‘repot’ it! Put it into a light multi-purpose compost, make sure it’s got very good drainage, keep it out in the sun again and don’t overwater it. You could use a John Innes compost. Make sure that the bottom of the pot has got crocks in it, it should then be fine so long as it’s got good drainage which is a key thing. And basically, cross everything...!”

Disinfecting greenhouses and pots
Q. What's the best way of disinfecting greenhouses and pots?

A. The best disinfectant, and readily available, is probably Jeyes Fluid. A good alternative is Armillatox, which is a general purpose garden cleaner: it can be used on pots, paths, greenhouses - and any passing garden gnomes.

Dried flowers, choosing plants for
Q. Please can you suggest some plants I can grow for dried flower arrangements?

A. There are some lovely plants which will dry well, and some probably more unusual than others. I would suggest the following: Alliums with their big, handsome globular seed heads, which should be cut and hung upside down in the shed in the summer; Phormiums, which produce slightly prehistoric flower spikes, again have fabulous dried seed heads; Hydrangeas dry especially well but usually when the flowers are nearly finished and the colours are at their richest; Vebena bonariensis is like purple Statice and again, cut and hang when in full flowers; and Poppies, the large oriental variety, produce classic seed heads for drying. For something slightly unusual try Agapanthus seed heads: once the seed pods have dropped, spray them silver to make fantastic decorations. You can always let nature help in the spring: look at the ground underneath large-leaved Magnolia trees, where you will often find perfectly skeletonised leaves – up to 12 inches long – try these for a different tablemat.

Drought, choosing plants to withstand
Q. Can you suggest some plants that will grow in drought conditions?

A. Quite a long list, but in general terms most succulent plants are well adapted to drought conditions. Similarly, a lot of the more aromatic plants like lavenders, thymes, rosemary etc enjoy those conditions. When it comes to trees and shrubs the minimum temperature for your garden will have more influence on your choice than dryness, surprisingly, trees like olives will happily grow in this country, especially in drier conditions - but I'm not sure I would want to try olives in deepest Scotland! Plants are often more adaptable than we realize, and once well-established will tolerate a reasonable measure of drought: but you only have to look at the plants that grow in Mediterranean countries to get more inspiration.

Duckweed, how to remove from a pond

Q. How can I remove Duckweed from our fish pond?

Duckweed in ponds is one of the most pernicious weeds, and probably one of the most frustrating. The best method for removal is by physical means: personally I find the risks associated with chemicals in ponds not worth it, unless we’re talking several acres of water here. The best tool for the job is a fine mesh children’s shrimping net, or a hoop of coat-hanger wire with an old stocking threaded through it and the ends of the wire pushed into a bamboo cane. And then all you require is time and patience, and – depressingly – some days there will seems to be more than there was yesterday. But be persistent, spend five minutes or so every day, and it becomes quite therapeutic, in addition you will eventually win.

Echiums, choosing

Q. Everyone knows the tall Echiums with the blue flowers. Can you suggest any other Echium varieties?

Echium pininana is undoubtedly the most popular, but you have to remember that the Echium family includes our native Bugloss. However, if you want other varieties that offer something similar to Echium pininana, then Echium candicans (fastuosum) has a RHS Award of Garden Merit, and is a nice dumpy form. Echium x scilloniense is a hybrid from Tresco, midway between the two. Echium pininana ‘Pink Fountain’ is a softer coloured but quite tall variety to ring the changes, and it’s worth remembering that all Echiums make good coastal plants.

Echiums, sudden wilting of young plants
Q. Why do young Echiums sometimes wilt suddenly and die?

A. Generally they're affected by a soil borne fungal infection, which is one of life's little irritations which we have to put up with. Try drenching with a general purpose fungicide. They tend to use mycorrhizal soil organisms and will generally do better when self-seeded from parents into soil than when you try lovingly to grow them in compost.

Eucalyptus, choice for small garden
Q. Please can you recommend a Eucalyptus variety for a smallish garden.

A. The best variety will probably be Eucalyptus nicholsii, which has small fine foliage and is much less vigorous than most, but bear in mind that all Eucalyptus are very tolerant of pollarding and you can maintain most varieties as a shrub by pruning hard every February, and that will encourage juvenile growth (in my opinion, the best bit of the tree). For the real Eucalyptus enthusiast, if you're ever in Wales, you may just want to visit the National Exhibition at Celyn Vale Eucalyptus Nurseries at Merioneth. Tel. 01490 430671.

Eucalyptus, cutting back
Q. We have a Eucalyptus tree which is now beginning to get in the way. Can I saw off one of its branches now (in May), or should I do it at another time of year?

A. Yes, do it now!

Eucalyptus, do they undermine?
Q. Is it true that a Eucalyptus tree can undermine a house?

The whole question of subsidence caused by trees strikes fear into the heart of every insurance company in the country. As a rough guide, unless you are on heavy clay soil, subsidence is unlikely to be a major issue. However, common sense dictates that you do not plant a large, vigorous tree five or six feet from your house, as the roots have to go somewhere! In the case of Eucalyptus, if you are planning to let it attain its natural height, I would not consider planting it within 20feet of a building. There are plenty of smaller and less vigorous trees which can be planted nearer the house.

Eucalyptus, keeps growing Q. We have a Eucalyptus. It’s 30 feet high, it’s next to the house and has been growing there for about fifteen years. We don’t know which variety it is, but when do you think it’s going to stop? What’s it doing under the house?

A. As far as the Eucalyptus is concerned, the sky’s the limit. And as my old boss used to say, ‘Plenty of room upwards, gal.’ They will keep going! For most Eucalyptus, if they’re ones like gunnii or niphophila which are the most commonly grown ones, growing to 80 feet (24m) is not out of the question. Now obviously they do make a substantial root system to support that and, if it is too close to the house, you do have a risk.
You don’t normally have a risk of subsidence unless you’re on heavy clay – the subsidence then is caused by the roots of the tree sucking all the moisture out of the soil, the soil shrinking – your house dropping. But what more often will happen down here is that the bulk of the roots become such that it can literally forge its way through something and crack it apart, so rather than causing subsidence, it causes – I don’t know what the opposite of ‘subsidence’ is? ‘\ Upsidence’? But it can push things apart and cause walls to crack, that sort of thing, it can cause paving to be pushed up, rather as if there’s a small volcano moving around underneath. Yes, that is an attendant risk.
If it is too close to the house, then one solution would be to pollard it every couple of years. If you don’t want to get rid of the tree, you like the foliage but you don’t want it to get any bigger, keep it down to something around ten or fifteen feet. The root system won’t grow bigger because it doesn’t need to. Root systems only grow as big as they need, to support the tree above. So you can curb its enthusiasm that way.
But if you let it go, you’re going to have almost as much underground as you have above ground. Something to bear in mind: that’s why I never recommend Eucalyptus as a wall shrub! It won’t be stopping at 30 feet!

Fasciation, causes of
Q. What is 'fasciation', and does it matter?

A. Fasciation is when you have two or more stems fused together. It usually happens with flower spikes and can produce some quite surreal flower effects. It is normally caused by nutrient imbalance or sometimes just the weather, but it occurs in the wild and is not a manmade problem. If you want to chop it off, fine. But if you want to watch it being weird, do so!

Fascicularia bicolor, description
Q. What is the name of the succulent which grows on the banks around the Lodge at the Loe Bar? It grows in large rosettes of long thin leaves with backward facing spikes. What is striking is its bright red centre.

A. I haven't been there, but this sounds like Fascicularia bicolor. It's only seen in coastal areas, usually in the west country. In fact, it's now indigenous in coastal areas in Cornwall and on the Isles of Scilly.

Fatsia japonica losing growing tip
Q. I have a Fatsia japonica which has lost its growing tip. What happens next?

In my own opinion, Fatsias are much better if they do lose that central tip, because it does encourage them to bush out. It does mean, however, that you’re going to end up with a very, very fat plant, because again it’s the nature of the beast with Fatsias. But it’s very rare for you to get one that continues to grow for very long with one leading tip: virtually always they will, one way or another, lose that growing tip and it will then shoot out and be multi-centred. But what I would suggest is that if the growing tip has gone, depending on how tall the Fatsia is, I would be tempted to have a look at it: if it’s over two foot tall and it’s only the tip of the growing bit that’s gone, I would prune it back down to around the two foot mark or maybe just under, and then that would encourage it to shoot out from lower down and make a more evenly bushy plant. If it starts shooting above two foot, you end up with a sort of half-standard effect which can look rather weird! So if it is the tip gone, then I would look at giving it a deliberate pruning.

Fragrant gardens
Q. Please can you suggest some fragrant plants for people with visual impairments?

A. Fragrance is a matter of personal taste, and what some people think smells nice, others may turn their noses up at. So for what it's worth, this is my list. Virtually all culinary herbs will provide a lovely aromatic flavour to your garden and indeed to your cooking. Roses are an obvious choice, but bear in mind that some modern varieties are not that well scented, so it's often better to choose a rose when it's in flower. Other aromatic shrubs for foliage include lavenders, Santolinas and Lippia. Cistus will give off a very Mediterranean aroma in hot and sunny wather. For flowers there's a huge choice, but some of my favourites include Viburnum, Clematis (particularly the montanas), honeysuckles and - surprisingly - Berberis. Hopefully this will be enough to make a start.

Fruit, taking hardwood cuttings of
Q. Is it possible (in late February) to take hardwood cuttings of Gooseberry and Black Currant?

A. Yes, it is. With hardwood cuttings, you can really carry on taking them pretty much until the new leaves come and the new growth starts. So there’s no reason not to take hardwood cuttings now and get yourself some little freebies growing along nicely.

Fuchsia hedge
Q. I am thinking of growing a Fuchsia hedge. How hardy are they? How do I propagate them?

A. Fuchsia hedges are an excellent choice and are reliably hardy in most coastal areas, however, if you lived on the top of Snowdonia there might be a problem! Varieties to choose would include Fuchsia magellanica and most of the F. magellanica varieties. Fuchsia 'Riccartonii' will also make hedges between five and eight feet high and which flower for months and months. Cuttings are very easy, take and treat as any other Fuchsia - in other words, take softwood cuttings in spring or summer.

Fungus, in compost
Q. There is a grey, fluffy fungus in the compost of the plant pots outside. What is it, and will it harm the plant?

A.If it’s a micorrhizal fungi, then that would be almost white, I suppose it is fairly fluffy – it’s like a bloom. It’s something that’s growing in a sort of symbiotic relationship with the root system. What it does in effect is to help the plant access nutrients from the soil and it will inoculate against diseases and infections. You can in fact buy micorrhizal fungi to use for that purpose, particularly when soils have been exhausted or you may have replanting. problems, they’re well worth using. So it’s possible that it may be that.Particularly with conifers you will find they produce their own micorrhizal fungi very quickly, which inoculates the compost in the pot. If you buy one, and you knock it out of the pot, you'll think ‘Oh, what’s all this white fluffiness?’ It’s good stuff, you certainly don’t want to get rid of it. Any other fungi that you find growing in the body of the compost, it’s very rare that it’s anything that’s going to be a problem: it may be something that’s come from the com post itself, it may be something that’s washed in, but soil is a living organism in itself, whether it’s artificial compost that you’ve bought as opposed to your garden soil they have lives of their own and ‘doddies' living within them and it’s very rare that that sort of thing could be an issue – you’re more likely to have a problem if there are pests in there rather than diseases. So I would say, on the whole, not a problem.

Furcraeas out of doors
Q. Can you grow Furcraeas out of doors?

Oh yes, very definitely. In fact, if you go to quite a few coastal places, you’ll see Furcraeas growing extremely successfully out of doors – the Isles of Scilly, where they almost attain weed-like status – the little bulbils that form on the flower heads will take root very easily. They’re not very frost-hardy. At the nursery, we tend to overwinter them in an unheated tunnel and they come through remarkably well. Bear in mind that this winter we went down to about -8°C, so they’ll take a reasonable amount of cold, so long as they’re dry. What they won’t tolerate is wet cold, like so many plants unfortunately. But yes, very successful in frost-free coastal conditions – very happy bunnies, seem to take just about anything that the weather can throw at them in that situation. And of course they’re such a wonderful architectural plant to have anyway. They don’t like it if it’s too 'cold cold' – but they’ll take the south-westerlies, the prevailing winds, the coastal conditions quite happily. I’ve seen fifteen-foot specimens on St Mary’s and Tresco – they’re quite fantastic, really impressive.

Geraniums from seed
Q. Please can you suggest some varieties of Geraniums (the Cranesbill sort, not Pelargoniums) to grow from seed in exposed conditions in West Penwith?

A. This depends on what's available. Most of these will do very well in an exposed situation. I would recommend having a look at a good seed catalogue for a wide range. Varieties of Geranium cantabriense or endressii would be good to start with.

Geranium maderense, how to grow
Q. Can you tell me how to grow Geranium maderense?

Geranium maderense, the same as with Geranium palmatum, over in this country where we do tend to get a higher rainfall are not the longest-lived plants in the world. They like to be grown in a relatively open position, more sun than shade, reasonably good drainage – not somewhere that gets waterlogged in the winter. After that, quite unfussy, they’ll take a fair bit of wind, they’ll grow on the coast and they’re very, very free-flowering. G. madarense has the finer cut foliage rather than G. palmatum. With both of them the flowers come up in sort of panicles above foliage and the whole of the top of the plant is like a dome of flowers and which goes on for months and months in the garden. It's a very beautiful plant. As for how long they live, it depends on the soil conditions. I would normally expect to get five years out of one, at least, it may well go on for longer. It will set seed if it’s happy, so you’ll have lots of babies coming on.

Geranium maderense, rotting
Q. Why do some of my Geranium maderense suddenly rot and die?

This is probably caused by the bad winter conditions, such as we’ve had this year. Even in a mild, coastal area it has still been very cold and wet for periods of time. I wouldn’t say it’s been a very wet winter, but any cold wet weather doesn’t suit them well. Strangely enough, if the plant’s been in a pot it can get heavily waterlogged without there being the capillary action of the soil to take the excess moisture away. Also, the frost can get right around the roots, which it can’t if the plant is in the ground. So I wouldn’t be very surprised if Geranium maderense grown outdoors in containers did not survive the winter – particularly the winter we’ve just had. There’s no one thing you can pin it down to, apart from weather, but it is a combination of the wet and the cold that I’m afraid has ‘done for’ them. But hopefully, if you’ve got some survivors and if they flower you can start some more off from seed and have some wonderful babies popping around the joint. But on the whole I’d say they’re happier in the ground. If they’re in a pot, I recommend that they go into a cold greenhouse or conservatory for the winter. Don’t remove the old leaf stems unless they’ve gone brown.

Gifts, practical, for gardeners
Q. Please can you suggest some practical gifts for gardeners?

A. If you’re stuck for a present for the gardener in your life, you’ve got several choices of direction. This week, we’ll look at practical presents. Depending on your budget, I’ve yet to find a gardener who would not appreciate a good stainless steel spade (or spade and fork), all nice and shiny with a big red ribbon on. Bear in mind, if you’re buying for a lady gardener, I personally find a border spade and fork better, and if your garden is very small, a border fork and spade fit in amongst the other plants more easily. But the guys like the big ones: I think it would be better if I don’t comment any further!
Another present which is always extremely well received is a really good pair of secateurs, and I have no hesitation in recommending the Felco range of secateurs, and my choice is always the Felco No 2, which I suppose I would class as professional secateurs – basic, unfrilly, very good – and I’ve had mine for over 20 years. And you can also, if you’re feeling flush, buy a proper leather holster to go with them. Luckily they do have bright red handles, so they’re not so easy to lose in the compost heap. At the lower end of budgeting, Burgeon & Ball do a lovely range of practical gardening gifts, ranging from very nice hand tools at around £10 a time, down to the dinkiest little oil can you’ve ever seen. It looks like a half circle with a long, pointy spout on it. You buy with it a very small can of proper white tool oil. You dip the pointy bit in and you press the button in the bottom of this middle round thing down so that it sucks some oil up into the nozzle and fills it. Press the bottom of the round part of the oil can and it just drips it out a drip at a time. It’s perfect for keeping all your hand tools in absolutely tip-top condition. Brilliant stuff.

Ginger, how to grow
Q.Can I grow Ginger for culinary use, and if so, how?

A. True Ginger is not frost-hardy in this country, but given the change in climate I would say that the areas it can be grown are increasing daily! Buy some fresh ginger root at your local fruit and veg shop, making sure it is plump and firm. Pot it up as you would a Dahlia tuber. You can then have your own source of the king of medicine. In effect, treat it like a Dahlia, protecting it from winter frosts.

Globe Artichokes, how to grow them
Q. How do you grow Globe Artichokes?

A. If you want them for eating, you should get them from a specialist supplier. You can usually find these in the back of the better gardening magazaines. As far as cultivation is concerned, they enjoy a fairly rich soil with good drainage. They do dislike excessive winter wet - but then, who doesn't? If you have a windy garden, I would recommend staking the flower spike as it starts to grow. The flower heads are very heavy, and if you fancy leaving a few on the plant, they are fantastically ornamental.

Grass, growing in perennial
Q. Have you any hints for removing grass from established clumps of perennials?

Quite tricky. It depends what sort of grass. If it’s Couch Grass, then you do have a bit of a problem on your hands because you’re trying to pull out a plant that is naturally invasive and seems to make a beeline for established clumps of things. If it’s annual or just ordinary perennial Rye Grass, you can just pull it out – in fact this time of year is a very good time to do it because perennials have only just started to shoot. If there’s enough of a handful of grass there, give it a good tug and a bit of enthusiasm with a fork underneath, you can very often lift the whole thing out and it will come away quite easily. If it’s an established clump but it’s something that wouldn’t object to being lifted, it may be that you can kill two birds with one stone and actually lift and divide your clump of perennials, replant it as a bigger clump but also at the same time remove any weed or grass or anything that is near the top of the clump – because most grasses are surface rooting (with the exception of Couch Grass) and you can deal with them that way.
If Couch Grass is a major problem, then personally I would probably recommend careful – and I mean the word, careful – application of weedkiller, something like Roundup or any glyphosate-based weedkiller. It needs to be applied very carefully just to the foliage of the grass, making sure that you miss the foliage of the actual perennial itself because it’s a systemic weedkiller and it’s one of the few ways that you will actually deal with Couch Grass, which is one of the worst things a garden can get!

Grasses, choosing ornamental
Q. Please recommend some ornamental grasses for planting in an exposed garden.

A. Grasses are a very versatile group and most are adaptable and suitable for exposed situations. However, if it's dry as well as exposed, then you may need to be a little more selective. Stipas, Festuca and Hakenechloa will all tolerate drier conditions, while Carex, Miscanthus and Panicum will all do better in a moister soil. There are many gorgeous varieties to choose from, from six inches to 10ft, and something for every situation.

Greenhouse heaters
Q. Please can you give me some advice about how to heat my greenhouse?

A. There