Knowing when and where to cut - demystifying the process of pruning

The idea of pruning makes most of us uncomfortable. So we tend to avoid pruning our plants until they've become overgrown, and we have to do something. But what, and how, and when?

The best time to prune depends on the type of plant. But you should always remove broken limbs and storm damage as soon as possible after they occur.

For general pruning, late winter is a good time to take care of most deciduous trees, shrubs, and vines (with some exceptions, which will be noted shortly). With no leaves in the way, it's easy to see what you're doing. Also, with spring just around the corner, the plants will soon begin to heal and grow.

In early spring, prune shrubs that flower in summer, broad-leaved evergreens, and all roses except climbers.

Prune spring-flowering shrubs in late spring, right after they've bloomed. Summer or winter pruning of these plants will remove the buds and prevent flowering.

In early summer, prune climbing roses as well as birch, dogwood, elm, maple, yellowwood, and walnut trees, which "bleed" (exude a lot of sap) if pruned in winter. Also, trim hedges and remove faded blossoms from rosebushes.

Avoid pruning in early autumn. It causes tender new growth that will be killed by cold.

The best way to deal with an overgrown shrub is to cut one-third of its stems back to the ground each year for three years. This will ensure that a shrub such as forsythia will retain its graceful shape and will continue to beautify your landscape even as it's being brought under control.

Many homeowners are comfortable with hedge shearing and tend to use the same technique on all shrubs. Big mistake. When you shear a shrub - cut all the stems back a certain number of inches - the result is exactly what you don't want - rampant regrowth.

That's because every cut you make at a random spot on a stem will result in at least two new stems. And soon they will need trimming, which will cause more growth that has to be cut - in an endless cycle.

To avoid this, use hand pruners or loppers - never hedge trimmers - and cut each overlong stem individually back to the main branch or trunk. This opens the plant to light and air, which help it grow better, but regrowth will be slow.

Yes, this method initially takes longer than shearing. But you save much time later by not having to cut back over and over.

When pruning trees, remove branches to where they're attached to the trunk. Don't cut off just part of a branch, and don't cut into the trunk; instead, stop at the swollen collar at the base of the branch. There's no need to apply wound dressing or paint; it can do more harm than good.

Remove heavy tree branches in three steps. If you try to make only one cut, it may tear the bark.

Often it's best to hire a professional arborist when dealing with large limbs and mature trees. Look for one certified by the International Society of Arboriculture.

Plants that require constant pruning are being pruned incorrectly or are growing in the wrong place. Sometimes it's best to start over, matching the mature size of a new plant to the site in which it will grow. That will reduce your pruning chores considerably.

(c) Copyright 2001. The Christian Science Monitor