Dr. Grow: Timing is crucial for pruning

In my last article I told you that I would discuss when to prune. Timing is determined by the species of the plant, the severity of pruning and the reason for pruning.

If you are concerned about a wild branch that seems to be growing out of proportion to the rest of the plant, remove it at any time. A plant that has a damaged, dead or diseased branch can also be pruned at any time. Timely removal of wild, dead, damaged or diseased branches will enhance the plant's shapeliness and reduce the chance of disease infection or insect infestation.

Although yews, boxwoods, hemlocks and arborvitaes can be pruned at any time, the best time to prune is early in the summer right after their spring flush of growth. Late spring pruning will result in that groomed look for most of the year. Refrain from pruning in the summer when it is hot and dry, conditions that stress a plant. Further stress on shrubs due to pruning could result in damage.

Pine and spruces should be pruned after their spring flush of growth, but before that new growth has hardened off. The best time to prune is during June and the first part of July. Cutting the new candles at this time will allow the tree to produce new buds at the pruning cut. If you prune hardened-off branches, no new buds will be formed and the pruned branches will remain as cut stubs.

Most orchardists prune in January and February because their view of the tree is not restricted by leaves and fruit. They can see which branches to eliminate and which branches to leave alone. Thinning at this time leaves fewer flower buds to open. Consequently fewer but larger fruits are formed.

Plants that flower in the spring, such as forsythia, viburnum and azalea, should be pruned right after flowering. These shrubs set flower buds in July, August and September for the next spring. If you prune these shrubs in fall after flower bud formation, you prune off all of the flower buds and no flowers will be produced the following spring.

Summer blooming plants should be pruned in the spring. Wait to prune crape myrtle and spirea after the spring flush. Remove dead branches at that time. If you want to greatly reduce the size of the plant, again, do it in spring. These shrubs set flower buds on this year's growth, so early spring pruning will not interfere with flowering.

Maples, birches and elms are considered bleeders. It is best to prune these trees in the summer because the tree sap will congeal soon after pruning. If pruned in the winter, they continue to bleed for a long time after pruning. This unrestricted bleeding results in the loss of tree vigor the following spring.

Trees and shrubs not discussed above, such as oak, hickory, ash, etc., should be pruned during the winter when dormant. These plants suffer less damage at this time.

My next article will discuss the methods and tools to use when you prune.