Some shrubs and trees require little pruning apart from removing dead or damaged stems, but for many others an annual trim is essential. Regular pruning can improve a plant’s appearance, stimulate the production of fruit and flowers, keep specimens youthful and vigorous, and encourage bolder foliage.
Routine pruning maintains the health and appearance of woody plants. In late winter or early spring, before the leaves of deciduous shrubs and trees appear, look at their overall shape in detail and identify branches that need removing or shortening. Also note any congested growth in the center, which can encourage disease. Then, cut away dead or damaged stems to healthy tissue; crossing branches that are rubbing and liable to create a wound; and stems that are no longer producing fruit or flowers.
Remove stems and branches growing at odd angles that look unsightly and may rub against one another, creating entry points for infection (image 1).
Cut back to young wood, which is often a different color and texture to the older, thicker stems (image 2).
Remove dead or infected wood to prevent further die-back or disease entering healthy tissue (image 3).
When pruning, use sharp clippers for thin stems, or a pruning saw for wood that is thicker than a pencil. Loppers are useful for chopping up prunings into more manageable pieces. Always make your cut just above a bud to avoid the stump dying back into healthy wood, and make clean cuts that will heal more quickly and are less prone to infection. To avoid wood ripping or splitting when cut, take the weight off long branches in stages. Cut to an outward facing bud, slanting the cut so that water will run away from the bud. Where buds are arranged in pairs, cut straight across the top. Two shoots will emerge.
When possible, remove tree branches when young, because the cuts heal more quickly. Most should be pruned in late winter, but wait until mid- to late summer for hornbeam (Carpinus), pears (Pyrus), plums and cherries (Prunus species).
Take some weight off the branch first to prevent it tearing close to the trunk. Cut partly through the underside of the branch; then saw from the top a little further up. Allow the branch to snap off.
Remove the final stump by cutting close to the trunk, but not flush with it. Make an angled cut away from the tree, just beyond the crease in the bark where the branch meets the trunk.
The result is a clean cut that leaves the tree’s healing tissue intact, speeding up its recovery. The wound may bleed after pruning, but will soon form a layer of protective bark.
This technique encourages climbers, wall shrubs, and trained fruit trees to flower and fruit more freely. Shortening the shoots that grow from the main stems promotes the remaining buds to produce far more productive stems than would normally appear.
Identify strong growing shoots and trim back to two or three buds from the main stems to form short branches or "spurs." Make a slanting cut to channel rainwater away from the chosen bud. This helps prevent disease and die back.
The "spurs" of this climbing rose will each produce two or three flowering stems in the forthcoming season. You can also spur prune wall-trained Chaenomeles, Pyracantha, and Ceanothus to keep plants neat and blooming well.
Wear thick gardening gloves when pruning or trimming, and use well- maintained tools appropriate to the task. Wear goggles and ear protectors when using a hedge trimmer. Don’t cut above head height; use ladders or platforms and make sure that they are stable and secure. Undergo approved safety training and wear specialist clothing before using a chainsaw.
Excerpted from How to Grow Practically Everything
© 2010 Dorling Kindersley Limited