How to prune acers, prevent 'wind-rock', and deadhead bush roses: top tips from our gardening expert

I am writing as the first salvos of what seems to be an early start to the now anticipated autumnal battle with the elements have left my last-legs hollyhocks leaning at 10-past-two and massed cosmos, planted on my allotment for picking, flat on their beautiful faces.

While felled flowers are of little consequence in the scheme of things, I am moved to address the subject of gearing gardens up for a windy winter. Here are my thoughts:

Trees, young and old

Trees obviously whip around alarmingly when they are in full leaf, as they are now. Most important are the youngsters, under two years old, which may still be reliant on the stakes that were inserted when they were planted. These should now have their support ties adjusted so that they do not chafe or constrict.

This is also a reminder to those who have large old forest trees on their property, that a lofty cladding of ivy makes tree canopies top-heavy, even when leafless in winter. It is therefore good practice to keep ivy out of tall trees.

Large and unruly bush roses

These may have roots that are quite small relative to their bulk, and can suffer from “wind-rock”. Check their stability now (and firm them down with your boot if necessary). Later in the autumn, cut out some of the height/weight to make them less vulnerable.

Rambling roses

They should have made masses of long new shoots that thrash around in the wind unless anchored down. Cut any superfluous ones, not forgetting that this year’s shoots will bear the best of next year’s flowers.

Climbers

Check that trellises, obelisks and such are firmly anchored and that the plants they support are well tied in. Late-flowering clematis whose performance is well and truly over (and for which February hard pruning is the norm) can be cut back now, to be revisited with the secateurs in spring.

Give wisteria its second cut and trim evergreen scramblers (for example, vigorous Trachelospermum and ornamental ivies) just enough to keep them clear of gutters.

Young hedges

Planted to become protective windbreaks themselves, they will benefit from protective artificial windbreak of their own for their first year (see premiernetting.co.uk).

New fences

Commonly available slatted fencing (that lets through the wind while scarcely compromising privacy) takes a battering better than solid fencing. Also, on the subject of privacy: fences and trellises to be adorned with climbers or used as a backdrop for tall shrubs really do not need to be above eye-height, since the plants themselves do the rest of the job.

Of course, this is just the tip of an iceberg. Most gardeners have a boring maintenance checklist involving niggles with gutters, downpipes, gates, greenhouses and suchlike.

We should aim to tick things off it during whatever Indian summer we may hopefully be about to have. From where I am sitting as I write, with wind howling and rain streaming down the window, there seems to be no sign of such a thing.

Bring out the kitchen fork

Susie Bishop has been struggling for two years to control a green-leafed shamrock-like oxalis; she has been using a hoe with little success. What can she do, she asks?

Actually, this little bulbous version of oxalis is, like the other described below, an extreme irritation to gardeners that like their plants surrounded by “clean” weed-free soil but not in any way crowding out legitimate bedfellows.

If necessary it should be tackled in spring (with a kitchen fork plus a pot for the bits) while the little bulbs are still green and don’t disintegrate (as they do when disturbed later, casting soil-coloured bulbils everywhere).

Hoeing in high summer is a no-no therefore and makes the problem worse. Thick mulches around fruit and veg that need little cultivation (such as rhubarb or raspberries) might help suppress it, but total control is nigh-on impossible.

The other common form of oxalis is driving Paul Whitby to distraction. This one has pretty reddish leaves, fine, brittle creeping roots and worst of all, tiny yellow flowers that produce explosive seed heads from midsummer onwards. Small eruptions of this plant (that is often introduced via potted plants from nurseries) should be treated to meticulous two-handed weeding sessions.

If flowers and therefore inevitably seeds are present, a small plastic bag can be used to cover each little plant before it is grasped, in an attempt to trap the seeds. I know, I know, a fiddle too far for most of us, but it all depends on how much one cares, I suppose.

Dear Helen

Five years ago, when redoing my garden, I moved a small, dark-leafed, Japanese acer to a prominent position in the middle of my lawn. It thrived and is now over 2m high, threatening to dwarf everything. If I cut 60cm off it, will it survive? I am a bit of a vicious pruner (witness a sorry-looking magnolia at the back of my picture), so I need some advice.

– Lindsay Housley, via email

Dear Lindsay

I will be quite candid: Acers do not take kindly to being roughly pruned and you could very well ruin another tree if you decapitate this one, condemning it to a life of haphazard management thereafter. The tree has beautiful foliage and is forming a good shape, I am sure you can make it look at home for a few years in the centre of your garden without “dwarfing” anything.

Start the ball rolling with some “transparency pruning” (i.e. tweak off with secateurs all the leafiness from the lower parts of its (apparently) several trunks, which will open its undercarriage so you can see through and beyond it.

Next, during the winter when the branch structure is clear to see, the canopy can be lifted by clean removal (back to the trunk) of a few of its lowest branches

If the tree still looks a little wide, cut out short lengths of the most wide-spreading branches, taking care not to give the tree a “blunt” outline. Look at the tree from every aspect as you work.

Helen’s tip of the week

As temperatures cool and light levels start to drop, make sure that tender succulents and leafy houseplants that have enjoyed the summer outdoors do not sit around in rain-filled saucers with constantly wet roots. And give them slug and snail protection for the next few weeks until they are returned indoors.

Get ahead of the winter protection game generally, preparing everything for plants that will need winter protection from next month: thoroughly clean out cold frames and greenhouses, clean the glass, clear leafy debris from the floor and from gravel trays and replace tired capillary matting.

Send your questions

Write: Gardening, The Daily Telegraph, 111 Buckingham Palace Road, London SW1W 0DT

Tweet: @TeleGardening

Email: helen.yemm@telegraph.co.uk

For more tips and advice from Helen Yemm, visit telegraph.co.uk/authors/helen-yemm.

• Read more: our guide to the best secateurs