The kindest cuts
Selecting the right shrubs and trees is the key to making sure plants don't overrun your home. But even when plants are selected properly, a plant that was supposed to grow to a certain height may exceed expectations. That's when it's time to prune.
Proper pruning techniques are essential to ensuring healthy and attractive plants. The goal is to remove diseased, damaged, or dead branches; thin crowded or rubbing branches; improve flowering; promote new growth; and maintain plant shape.
In general, shrubs that flower before June 15 should be pruned in the spring after flowering. Spring-flowering shrubs develop buds during the previous summer or fall. Pruning these shrubs before they bloom will reduce flowering.
Shrubs in this category include deutzia, forsythia, kerria, lilac, mock orange, red-twig and yellow-twig dogwood, weigela, and viburnum. To encourage new growth of spring-flowering shrubs, prune immediately after bloom. Pruning after bloom give the shrub time to initiate new flower buds for next year. Remove up to one third of the old stems to ground level.
Summer-flowering shrubs, such as spiraea and potentilla, are best pruned in late winter or early spring, before they begin to leaf out. These shrubs bloom on the current year's wood.
Before pruning, examine the plant carefully. Decide what should be pruned out and mark the branch with a colorful ribbon or paint. Then step back and visualize the plant after the cuts. Does the plant look the way you want it to? The practice of marking branches will also keep you from pruning the wrong branch.
Some different pruning techniques:
Renewal pruning or thinning of multistem shrubs encourages flowering and fruiting. Remove a third of the oldest stems at ground level. This will encourage new growth. Some shrubs that benefit from renewal pruning include lilac, weigela, forsythia, red-twig dogwood, and deutzia. Generally, larger shrubs are subjected to renewal pruning.
Rejuvenation pruning of shrubs is the complete cutting back of all stems to about four inches above the ground. The best time to rejuvenate a plant is in the spring. Some shrubs that respond well to rejuvenation pruning include Anthony Waterer spiraea, Little Princess spiraea, honeysuckle, privet, butterfly bush, and beautybush. Rejuvenation pruning is generally performed on smaller shrubs or those that become a tangled mess of stems.
Heading back refers to cutting a branch back to a bud. A cut is made on a slight angle, a quarter of an inch above a healthy bud. The bud should face in the direction of preferred new growth.
Shrub pruning requires a good set of pruning shears or loppers. Pruning shears cut branches that are as large as three quarters of an inch in diameter. Lopping shears are designed to cut branches three quarters of an inch to an inch and a half in diameter. Pruning saws are used for branches larger than an inch and a half in diameter. To help prevent the spread of diseases, disinfect pruning tools with denatured alcohol or a 10 percent bleach solution.
A few pruning don'ts:
The use of pruning paint or wound dressing is no longer considered necessary and may actually slow wound closure.
Avoid pruning shrubs and trees in late summer; such pruning may encourage a late flush of growth, and the new growth may not harden off before the arrival of cold weather.
Not only can incorrect or severe pruning of trees and shrubs cause stress to a plant, but it can also make the plant weak and more susceptible to disease and insect problems.