Knowing when to prune different species of plants is a skill that many gardeners fail to grasp. Many plants have an optimal time or season when pruning should be done.
Often we prune to direct the growth or train plants into a certain form or to fit within a certain space, such as a hedge.
Annual pruning is used to control the size and shape of mature plants, as with landscape trees pruned away from a building, or fruit trees pruned low to aid in harvest.
Pruning also plays an important role in opening up a plant to more sunlight which can induce the growth of renewal wood. This is important in maintaining healthy foliage, flowers and fruit.
Pruning is often seen as a job set aside for late winter while the plants are dormant.
In many cases, late winter is the best time.
However, selected pruning and training techniques can be applied during the summer months to remove unwanted growth before it develops and to direct the plant's energy into more permanent and desirable areas.
Keep in mind the main objective of your pruning job when considering timing, severity and method. Time of pruning can vary with the plant species, growth characteristics and flowering habit.
Spring-flowering plants, such as apple, crabapple, dogwood, peach and forsythia can be pruned after they bloom. Flower buds on these trees form in the summer and bloom the following spring.
Pruning spring-flowering plants during the late season will remove flower buds formed the previous year, resulting in a loss of blooms. Pruning immediately after bloom stimulates new growth, which provides more flower bud potential for next year.
One of the most common questions I get is when to prune blueberry bushes. These should be pruned immediately after the bush stops bearing fruit in the summer. This gives the bushes time to grow new wood and set fruit-bearing buds for next season.
Most summer-flowering plants produce flower buds on early spring growth. Pruning on these trees and shrubs can be done in late winter. This will help stimulate new growth and flower buds.
Undesirable shoot growth, such as suckers and water sprouts, can also be pinched or pruned out during the summer.
Young trees with a single trunk often begin to develop multiple leaders. Shoots competing with the leader trunk should be pruned out early. Side limbs that interfere with the overall tree's appearance may also be pruned out.
Summer pinching or pruning cuts may also be used to direct growth in a certain direction. If a limb near a patio is growing into the space, prune growth back to a shoot growing upwards or away from the patio. This will help you avoid larger pruning cuts in the future.
Minor pruning and pinching can be used throughout the summer season to control unwanted shoots and direct growth into a more permanent form. These techniques are used by orchardists and tree farmers to develop good tree structure.
Heavy pruning should be avoided in the late summer and fall. Pruning at these times promotes vigorous new growth late in the growing season, which makes the plants more susceptible to frosts and freezes. For most plants, avoid pruning more than one-third of the entire plant at one time. This will help maintain a healthy root system.
Clark MacAllister is the Dawson County extension agent. For more information, call (706)265-2442.