Pruning trees and shrubs: It’s all in the timing

As the days get longer, our attention turns to spring chores. One of those is pruning. Late winter is an excellent time to prune many landscape plants, but not all.

Late winter is ideal because deciduous plants have no leaves, making it easy to see the branch structure and where to make the cut. Pruning creates a wound. As plants prepare for spring they go through a phase of rapid growth. This growth helps the plant seal off wounds for quick healing.

The right time to prune is based on more than just ease and recovery time. It’s also based on each plant’s growth habit, bloom time and other factors that contribute to a healthy plant. Clip this guide and hang it in your garden shed.

▪ Late January through mid-March: This is the ideal time to prune ornamental shade trees. Oaks, locust, and many other species can be pruned now. The exception would be maples and birches; they ooze or bleed if pruned prior to bud break. While this does not harm them it does cause concern. Prune these trees after they leaf out to reduce sap bleeding.

▪ Mid-March through mid-April: This is the ideal time to prune summer flowering shrubs. They bloom on new growth produced during the summer. Butterfly bush, dwarf spirea, rose of Sharon, roses and burning bush are shrubs that bloom in the summer. Pruning stimulates new growth that produces summer flowers.

▪ Late April through June: Prune spring flowering shrubs and trees. Examples would be lilac, forsythia, crabapple, azaleas and redbud. These plants just finished flowering and will set next year’s blooms on new growth produced during the summer. Pruning before they flower in the spring removes the blooms. Avoid this common mistake.

Evergreen trees and shrubs are also best pruned at this time. Yews, junipers, boxwood, spruce, arborvitae and pine can be trimmed. Pruning these plants can be tricky based on their various growth habits.

▪ July through September: Little or no pruning should occur during this period. Pruning can be stressful for plants in summer. Pruning stimulates growth, and this is a period when the plants work on internal processes not vegetative growth. The exception would be to remove dead, dying, broken, damaged and hazardous limbs. Suckers, water sprouts of other growth that compromise the desired structure of the plant can be pruned.

▪ October through late January: Plants are going dormant in the fall, and pruning opens wounds that could be damaged with harsh winter conditions. The wound created does not heal quickly, leading to more insects and disease. It is permissible to cut twigs of evergreens and shrubs to use in holiday decorating or forcing for late winter blooms. Now is a good time to negotiate pruning contracts for the next year.

This is a very simplified explanation of pruning, but it should help you make better decisions about when to prune the various plants in your landscape.

This story was originally published February 10, 2017 at 12:00 PM with the headline "Pruning trees and shrubs: It’s all in the timing."