How to Prune TreesWhether it is to improve the shape of a plant, to make it produce more flowers or fruit, or to correct some damage, pruning is an important part of the procedure for maintaining the health of many plants. On some plants, pruning is an annual procedure, carried out to keep the plant to a suitable size or to encourage it to produce larger flowers, more fruit or better colored stems. On others, it is an operation carried out occasionally, perhaps as a result of damage, to prevent the open wound becoming infected and harming the plant. As a matter of routine, every plant should be checked regularly for signs of the “three D’s”, disease, damage and death.
If a diseased branch is caught early, and pruned back to uninfected wood, there is less chance of the problem infecting the rest of the plant. Areas of damage expose the tissue underneath the bark, and are ideal sites for fungal spores and diseases to enter the plant. Dead branches can also act as hosts to fungi and diseases, some of which can easily travel into the living tissue and damage it. Any suspect shoots should be pruned back to clean, healthy tissue as soon as possible, using clean equipment.
Types of Pruning
The main types of pruning are:
- Formative pruning, when the plant is young, to encourage the early development of a strong frame work of branches.
- Containment pruning, where, as the plant ages, it is regularly pruned in order to keep its size and shape within the constraints of the garden.
- Remedial pruning, when the “three D’s” rule is put into operation, to maintain the health of the plant. Remedial pruning is also used to eliminate any crossing or congested branches and, on variegated shrubs, to remove any shoots which have reverted to plain green (variegated shoots are weaker than green ones, as they contain slightly less chlorophyll, so that if the green ones are left in place, the whole plant will revert).
Timing the pruning operation correctly is critical to the performance of the plant; if you prune at the wrong time, you may cut off all the flower buds for the season. Not all plants can be pruned for the year in early spring; in fact, the best time to prune many, especially flowering shrubs, is right after they have flowered, so that they have the maximum time to develop their buds for the following season.
MAKING A GOOD CUT
One way of gaining confidence when pruning your climbers is to learn how to make the correct cuts. Always use sharp secateurs (pruners) or a sharp saw if you are cutting larger branches. Pruning cuts should always be clean; try not to bruise or tear the wood by using worn or blunt secateurs.
Cuts to remove main stems or thick stems branching off the main stems should be made close to their origin, making certain that there is no “snag” or stump left. On the other hand the break should not be so tight that it cuts into the parent wood. Thinner stems should be cut back to a bud, leaf joint or the previous junction. Make the cut just above a bud. This bud should usually be an outward-facing one, so that future growth is away from rather than towards the centre of the plant. The cut should be angled slightly away from the bud. If the leaves are in pairs on the stem, one opposite the other, make the cut straight across, rather than sloping. The position should be the same, just above an outward facing bud.
PRUNING WINTER DAMAGE
Some plants, such as shrubs of borderline hardiness, may be damaged but not killed by a cold winter. In spring cut out cold damaged shoots. Remove the affected tip only. This will greatly improve the appearance and new growth will soon hide the gaps.
PRUNING A NEW HEDGE
If you buy plants sold specifically for hedging they are likely to be young plants with probably a straight single stem. These keep the cost down, but formative pruning is particularly important to ensure that they make bushy plants later on.
New shoots will be produced if you cut back the main (leading) shoot to about 15 cm/6 in after planting. Trim these back by about half in early or midsummer. If you buy bushy hedging plants, shorten the height of these plants by one-third. Do not remove the main (leading) shoot of a conifer, large leaved evergreens such as aucubaor laurel, beech or hornbeam. Trim that off only when the hedge is approaching the desired height. If you like, shorten other shoots on these plants by between one-quarter and one-third, to stimulate instead bushy outward growth.
FORMATIVE PRUNING FOR SHRUBS
- The best time to prune shrubs is as soon as possible after the flowers have faded. Shorten the growth from the last summer by half. It will be paler and suppler than older wood.
- Avoid cutting into dark, older wood as new shoots are seldom produced from this.
- From a distance the difference after pruning will not be obvious but it should be neater and more compact. The real benefit will be cumulative. Remember to start pruning while the plant is still young.
CONTAINMENT PRUNING FOR SHRUBS
- Simply cut back all the previous summer’s growth to within about 5 cm/ 2 in of last year’s stem. Do not worry if this seems drastic. The plant will soon produce vigorous new shoots and replace the ones you are cutting out.
- Cut back to just above a bud. Keep to outward facing buds as much as possible to give a bushier effect. Most of the shoots should be cut back to within about 5 cm/2 in of the base of last year’s growth, but if the bush is very old, cut out one or two stems close to ground level. This will prevent stems rubbing against each other, and improve air circulation.
- This is what a plant that has been cutback to a low framework of old stems looks like. Try to keep the height after pruning about 90 cm /.3 ft or less.