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Why do we prune plants

01:00 Thu 07th Mar 2002 |

A. There are a number of different reasons why we go round the garden lopping bits off here and there.

There is the formative function, either to keep a plant within certain bounds or to encourage it to grow to a certain shape and the health function, cutting out diseased or weak growth that could undermine the plant.

However, the principal point of pruning is to promote fewer and stronger shoots and so better growth and, in many cases, more flowers.

Q. Which types of plant do you actually prune

A. Annuals don't need pruning. As their name suggests they only live for a season. Perennials often need dead growth cutting back and dividing, but this isn't really pruning. The term pruning is associated with shrubs, including climbers, and trees.

Q. What sort of equipment do you need

A. You'll need a good sharp set of secateurs for a start. Although you can get very cheap pairs these days they don't last long so it is probably worth your while in the long run investing at least a tenner in a decent pair.

A pair of long handled loppers, essentially large secateurs at the end of a long pair of handles, are invaluable for thicker and high up growth and if you are going to be pruning trees you will a narrow bladed pruning saw. And don't forget a decent pair of gardening gloves if you are dealing with thorny plants like roses.

Q. Right, where do we start

A. Have a good look at the plant first. Any dead, diseased or spindly growth can be removed right away, cutting right back to healthy wood. If two braches are crossing, take the most awkwardly placed one out, again right back to the main stem.

Pruning for shape or to encourage growth is done between buds on the stem. Generally speaking buds are either opposite each other or alternate up each side of the stem.

Where they are opposite, once you have worked out whereabouts on the plant you need to cut, make a clean horizontal cut about quarter of an inch above the buds. Where they are alternate the cut needs to be slightly angled, starting on the opposite side to the bud and sloping upwards to end again about quarter of an inch above the bud.

Bear in mind that whichever way the bud is facing is the way the new shoot will grow. This is important when pruning to shape. If, for instance you want to prune a shrub to stop it growing over a path you need to prune back to a bud that will grow in the opposite direction.

If you have a tree or shrub that is lopsided, growing more vigorously on one side that the other, prune lightly or not at all on the dominant side and hard back on the weaker side.

Q. When do you prune what

A. There no hard and fast rules and there are pruning jobs in the garden throughout the year. Basically you need to find out if the plant in question flowers on the current year's growth, in which case they are generally pruned in spring, or last year's growth, in which they should be pruned immediately after flowering.

Shrubs grown for their winter colour such as dogwoods and willows should be pruned hard back to within a few inches of the ground in early spring.

Q. What about trees and climbers

A. Young trees generally only need pruning to develop their shape. When young, shoots that appear from the main branch that will become the trunk should be cut off straight away.

Deciduous trees are pruned in winter while they are dormant while evergreens rarely need anything but formative pruning, which is carried out in mid to late Spring.

Climbers again depend on when they flower. Late flowering climbers generally flower on the current year's growth and should be pruned to the older wood in spring while the early, spring flowering group should be pruned after flowering.

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By Tom Gard

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