Pruning trees and shrubs

Pruning is an operation which regulates and controls growth, flowering and fruiting. With pruning, the form of a tree or shrub is determined. Pruning occurs in nature by twig-shedding (or after ice storms!), but nature’s end result might not be desired for our home gardens or urban environment. Although many of our favourite horticultural specimens require little or no pruning to maintain their shape, flower or fruiting habits, we often need to step in.

The Maintenance of Plant Health. Cutting out dead or damaged growth removes a possible source of infection. The removal of thin, weak growth from the centre of a tree or shrub encourages a free circulation of light and air; increasing the overall health and vigor of the plant.

The Maintenance of Shape and Balance. In winter, when the leaves are down, it is easiest to see the branching structure. Overlapping branches become obvious along with imbalances in the shape caused perhaps by growing in the shade or if a branch was removed from damage or disease. Pruning in early spring, prior to growth beginning, is the best time to adjust the shape and balance of a tree or shrub. Fruit trees should be pruned in early spring to maintain strong, balanced growth which can sustain the fruit load.

Pruning for Decorative Effect. Hedges, topiary, bonsai and espalier are all examples of how pruning can manipulate and alter the look of a plant.

How to Prune. Pruning is both an art and a science. It entails looking ahead and anticipating what the results of a particular cut will be. Pruning will stimulate growth from the bud immediately beneath the pruning cut. Consider the direction the remaining bud is facing and what long-term effect this will have on the shape. Cut a branch back to the next main stem rather than shortening the branch or you will get a tufted or “broom” appearance.

Secateurs are the most suitable tool for most cuts or a pruning saw for larger branches. The cut needs to be as smooth as possible so that healing is more rapid; achieved by using sharp, quality tools. The cuts should be made on an angle to prevent water from collecting in the scar, and as close to the remaining bud as possible.

When to Prune.

1. Never prune in the fall! Pruning stimulates growth which will be too succulent for late fall conditions.

2. Prune to allow the plant as long a growing period as possible in which to produce wood of the desired type. Spring flowering shrubs should be pruned after flowering since flower buds are present on the older wood. Late spring or winter pruning would remove flower buds. Examples: Lilac, Weigela, Rhododendron, Forsythia.

Summer flowering shrubs and roses should be pruned in early spring since flower buds are formed on the new wood. Examples: Rose of Sharon, Smoke Bush, Butterfly Bush

3. Prune prior to a period of active growth to encourage spreading. Vines and ivies will form a dense cover more quickly if pruned annually. Each species is different in its response and sensitivity to pruning. To be wise, gardeners should check with a local horticultural expert for rare or unusual specimens.