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Weeds in awkward places, fruit tree advice
Weeds v. cotoneaster
How I can control weeds that pop up among the matted stems of a groundsmothering cotoneaster that covers a long bank? Or do I have to weed it by hand? GAVIN LICKLEY, VIA EMAIL
This is a tricky one. Your pictures showed wisps of grass, colonies of dandelion and a few stray tendrils of vetch. Not a serious infestation, but irritating and hard to deal with on a well-covered slope.
The dandelions are the biggest eyesore, and have the deepest and most tenacious roots.
I suggest that you cut away the cotoneaster around the colonies in order to use a weed killer. Applying ready-mixed Roundup on the “foam” setting during dry weather should weaken them, but another go may be necessary in the spring.
Alternatives such as a teaspoon of salt in the centre of each leaf rosette or a spritz of vinegar may kill the top growth but not the roots. The cotoneaster will recarpet the exposed soil quite quickly. The grass and vetch may need a concerted effort with gloved hand and small fork, I am sorry to say.
War of the roses
I have to replace some wornout roses and have had conflicting advice. On one hand, I’m told to plant a new rose in the same site. On the other, I am told that would be disastrous, and that I should find a fresh site (not possible, as this is a formal rose bed), or dig out the old site and plant the new roses each within a cardboard box filled with soil. GERALD GOUCHER, VIA EMAIL
This is all about what is known as replant disease or, in the case of roses (which are particularly susceptible), “rose sickness”, whereby replacement plants of the same family fail to establish. It is thought to be caused by microscopic soil pests or pathogens.
You should ignore the first rather gung-ho advice. Instead, remove the worn-out roses and replace the soil they were in (to a depth and width of about 1½ft/45cm) with some from elsewhere in the garden, enriching it with organic matter and a fistful of rose fertiliser (or blood fish and bone). Planting the rose with mycorrhizal fungi (Rootgrow) is also said to ensure rapid establishment. The cardboard box idea sounds gimmicky, but it is favoured by many, and instead of using garden soil, you could use John Innes no. 3 mixed with extra organic matter.
We have a skimmia bush that has outgrown its space. It looks healthy on the outside, but is mostly bare-stemmed beneath the attractive canopy of colour. Should we give it a hard pruning in spring to renovate it? FIONA MERRICK, VIA EMAIL
Lucky you. From your picture, it is clear this is a splendid self-fertile
Skimmia japonica subsp. reevesiana, which has scented flowers as well as red berries, with no need for a mate. It would be a shame to lose it, but it may be too old to move.
You may have read elsewhere that skimmias don’t like to be cut right back, but in fact there are few evergreens that won’t eventually shoot out, even from bare wood, if thus treated. To give you some encouragement, a happy and healthy Skimmia x
confusa ‘Kew Green’ in my garden was savagely cut back to within inches of the ground and left for dead two years ago (I was clearly out of sorts and having an Attila the Hun gardening moment). After a laboriously slow recovery, it is now looking rather chipper and will probably flower next year. (You don’t have to do Attila-pruning on yours, of course.)