Shrub Maintenance

My holly bush never seems to have any berries. What is wrong?

Hollies (Ilex) come in male and female varieties and only the female ones bear berries. What is more, they have to be pollinated by males if fruiting is to be sucessful. It sounds to me as if you have a male bush and your neighbours have females, so your tree is pollinating theirs. I suggest you buy a variety like ‘J.C. Van Tol’ or ‘Golden King’ (both of which, just to confuse matters, are actually female).

My camellia ‘Donation’ grows well but does not flower. What can I do about it?

Camellias need a moist, free-draining soil on a site that is sheltered from the strongest sun and, more particularly, sheltered from the early morning sun in winter. They are not tender plants but the flower buds are often damaged through thawing out too quickly. They then go brown and drop off. This happens when bright morning sun strikes the buds after a frosty night. I suggest you either move your camellia or plant another evergreen to shade it on cold winter mornings.

How do I make my hydrangeas bear blue flowers?

If your hydrangeas are pink, the chances are that you live on an alkaline, limy soil and they are unlikely to go blue even if you plant blue-flowered varieties such as ‘La France’ or ‘Lorelei’. The answer is to dig in plenty of peat when planting, to mulch with peat every spring, and to apply a special blueing powder containing aluminium sulphate. Watering with what are called sequestered minerals can also help. On limy soil hydrangeas and some other shrubs cannot take up certain plant food. But if these are made available in their sequestered form, the plants can absorb them.

The magnolia I bought at the garden centre last year has not flowered. Should I take it back and complain?

Some magnolias flower very early in life, but others do not. If the plant you have is Magnolia stellata you have cause to be worried as this compact variety does tend to flower quite happily when young. M. soulangeana, however, sometimes takes quite a few years before doing its stuff. A regular mulch will help keep it happy, but there’s little more you can do other than wait.

Couch-grass seems to be creeping farther and farther through my hydrangeas. Do I have to dig them all out to get rid of it?

Couch-grass is a particular problem with shrubs such as hydrangeas, St John’s wort (Hypericum), and mock orange (Philadelphus) that produce dense basal growth. Until recently you had to do exactly that, but now there are two ways of dealing with it. A new weedkiller containing alloxydam-sodium has recently come on to the market which kills couch-grass and similar creeping grasses but not broad-leaved plants. You can spray it over shrubs or herbaceous plants and it will not harm them but willkill the couch. Alternatively, use the weedkiller glyphosate, which comes as a gel. With a brush in the lid of the tub, and can be painted on the couch leaves. If you get any on your shrubs it will damage those, too, so be careful in applying it.

How can I stop the birds eating the berries on my pyracanthas and other shrubs?

Training a cat to sit by the bush is perhaps the best answer! There are various spray-on repellants which deter but do not harm birds, but heavy rain much reduces their effectiveness. If you look around, you may find that the birds like some varieties less than others.

I have a problem with bindweed. It climbs up through my philadelphus, and although I keep pulling it out I can never get rid of it. What should I do?

The trouble with bindweed is that its roots are very deep and full of food reserves. You can kill it by repeatedly pulling or hoeing the tops off, since you will thus prevent it from producing food. But if it is right in amongst a shrub I would suggest a different approach. Unwind the bindweed from the stems of the shrub and then treat them with a weedkiller. Either paint the shoots with glyphosate gel or mix up some 2,4-D lawn weedkiller in an old jar or basin and dip the stems in the solution. The weedkillers will be carried right down to the root and kill the weed for good. Be careful not to get any chemical on the leaves of the shrub.

I have a hibiscus which had beautiful flowers when I bought it but, although it has seemed to be healthy since I put it in, I never get any flowers. Is there a reason for this?

It sounds as if your hibiscus is not in the right position. Hibiscus syriacus demands full sun, and unless it gets it, it is unlikely to flower. In colder areas the plant needs the additional protection of a warm, south-facing wall.

The leaves on my pieris are going yellow around the edges and the bush doesn’t seem to be growing very strongly. What is wrong with it, and what should I do!

This sounds like a classic case of lime-hating plant growing in soil with too much lime in it. You can help by watering with sequestrene, which will improve the health and colour of the pieris; but if the soil is basically not suitable, you are fighting a losing battle.

The ceanothus that has been growing on my wall for about 10 years has recently started to go back. The shoots at the base suddenly go limp and die off, and I have noticed a stain creeping up the stem from about soil level. What is wrong with it?

I think this is probably root trouble. My guess would be that the soil is very wet deep down. This may be due to a fractured drain or broken gutter or downpipe, or possibly to a nearby soakaway. Check all these possibilities. The only alternative I can think of is that the area was used as a dump before the house was built, or during the building, and that something toxic was left there. Your local council may be able to help.

I have a spotted laurel, and one of its branches has suddenly gone dark brown and then black for no apparent reason. Why?

This is a difficult one. Most spotted laurel (Aucuba japonica)plants seem to do this at one time or another, and there does not seem to be any logical reason for it. As soon as you notice this happening, cut out the affected part; new shoots will soon fill the space.

Some of the shoots on my brooms have grown very flat with lots of shot side shoots. Can you tell me what causes this, and is there anything I can do about it?

This is caused by buds not forming properly in the tip of the shoot, and it is called ‘fasciation’. It can be caused either by damage to the shoot tip or, sometimes, by damage from pests, or by conditions which promote exceptionally rapid growth. The answer is simply to cut the shoot out entirely.

I’m worried about the possibility of my children being made ill by eating berries and leaves in the garden. Can you tell me which shrubs are poisonous, so that I can avoid buying them?

The main ones to avoid are: yew (Taxus), box (Buxus), cotoneaster, laburnum, mezereon (Daphne mezereum), ivy (Hedera), and sea buckthorn (Hippophae rhamnoides). Do not forget that some trees and perennials are poisonous, too.

28. October 2013 by admin
Categories: Featured Articles | Tags: , , , , , , | Comments Off on Shrub Maintenance


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