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Dave Allan on pruning

Pick your moment and prune with care to give your precious trees and shrubs a fighting chance.

If you haven’t got round to pruning this winter it’s maybe just as well, given the recent weather. Snow and strong winds cause much damage, but wait till the worst is over before wielding the loppers.

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A shrub may look congested, but tightly knit branches trap and warm the air inside, creating a micro-climate that provides a degree of protection during severe weather. Also, freshly exposed branches may not be strong enough to withstand gales.

Dead or diseased branches must also be removed. Cut dead sections back almost to the join with live wood, and diseased ones well into healthy wood.

Die-back is a familiar problem when you prune too early. How often have you had a satisfying pruning session in the orchard, followed a few days later by a severe frost, with resulting die-back? When you prune a branch, the plant immediately starts to repair the damage by covering the cut with a callus, but when the tree is dormant, this process will take longer, and cankers and other pathogens can enter the wound. Frost damage caused by water freezing on or near the cut can also cause die-back. (I’m never tempted to paint a new cut with a protective seal, such as Arbrex, since I think this makes it harder for the tree to heal itself.) A late prune will make die-back less likely.

Apart from dealing such emergencies, pruning is an important way of creating or maintaining good shape, restricting growth, or, in the case of shrubs, preparing for a better show of flowers. With a bare, deciduous tree, it’s easier to judge which branches should be removed, either to keep the shape you want or to cut back an over-vigorous stem. With fruit trees, keep the centre open to encourage a good airflow and let the sun ripen more of the fruit.

It’s usually best to cut out one whole branch rather than nibbling at two or three. By removing a large branch in sections, lopping off all the smaller laterals, no damage is done to the rest of the tree. It’s astonishing the difference this will make to the overall appearance of the tree.

When it comes to removing the branch from the trunk, avoid sawing flush with the trunk because the wound you make will be too big to heal properly – but take care not to leave an ugly protruding stump either. Where the branch and trunk meet you’ll see a bark ridge above the branch, and a swollen area, called a collar, beneath the branch. Saw on a line just outside the ridge to the outer point of the collar beneath, being sure to avoid ridge and collar. That’s the ideal, although it’s not as easy as it sounds when you’re halfway up a ladder with another branch sticking in your ear.

This type of pruning is one of the most rewarding gardening jobs, but try not to go mad with the secateurs and check your tree or shrub should be pruned in winter. Apples and pears, for example, should be hard pruned in late winter, but only every few years. Light summer pruning to stimulate fruit buds is usually all the tree will need. Plums, peaches and cherries should never be pruned during the dormant season.

When it comes to deciduous ornamentals, winter is certainly the time to do whatever hard pruning is needed. If you have to tackle major renovation, spread pruning over three years and feed the shrub or tree while doing this. In the early spring after pruning, lightly scatter chicken manure pellets or seaweed meal round the plant – overfeeding will stimulate too much leafy growth. Then, when the soil is moist, apply an organic mulch – muck, compost, woodchip or leafmould. This way, your victim will recover from its shock.

Once established, most trees and shrubs need only a light shaping and the time for doing this varies from species to species. Hawthorns (Crataegus species) may become congested in the centre and require some thinning out as will hazels (Corylus species) and willows. Leave early-flowering types such as witch hazel (Hamamelis) and Forsythia until after they have flowered or you will be cutting off all the flower buds.

Restrict yourself to cutting only what is essential. Each wound you make weakens the plant, reducing the energy the foliage receives from the sun through photosynthesis. A light touch with the secateurs is often the best prune.

SUSTAINABLE PLANT SUPPORTS

Instead of throwing out your prunings, put them to good use in the garden. Shredding the branches would make a good woodchip mulch, but fan-shaped branches of almost any size make ideal plant supports.

First, cut them to the sizes you need, then put the twigs round the plants so the plants grow through the little branches, which should virtually conceal the supporting twigs. Even if you do catch a glimpse, the fan looks far more natural and attractive than an expensive bit of plastic from a garden centre could ever do. You’ll stop plants from flopping on to a path, or support tall, brittle flowers such as lilies.

Peas and runner beans will happily start growing by clinging on to small twigs, and any tall, straightish poles make perfect supports for tomatoes or cucumbers. The list is endless: recycled garden rubbish is free and may do the job well.

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