From Dennis Patton:
Each fall our office receives a number of calls about pruning. The pruning questions range from roses to oak trees. I guess the callers are really not asking a question, but instead more for permission to prune. It seems for some reason people feel the need to prune in the fall.
Fall is not the ideal time to prune. I am not sure where people get the idea that fall is a good time to prune. Let me explain why fall pruning is not highly recommended.
But first it’s important to review a few basic pruning facts. Pruning is good for the overall health of the plant. We prune for a number of reasons, including improved structure, flowering and fruiting. Pruning in general is part of an overall plant health maintenance program. It is also important to remember that making a pruning cut results in an injury to the plant. The plant tissue is wounded and time is needed for it to heal.
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Ideally we would like for the wound to heal, or seal over as rapidly as possible. Open wounds can be the entry path for insects, disease, rot and decay. For this reason, pruning of trees is best done in late winter. The wound is created just before the season of active growth and the plant can start the repair process.
Fall pruning allows for an open wound for a longer period of time. I believe some may recommend pruning in the fall because the likelihood of insects and disease affecting the tree over the winter months is extremely low. So technically fall pruning would be better than summer pruning.
Take the case of oak trees, for example. Since a nasty disease called Oak Wilt has moved into the area, the recommendation is to not prune oaks during the growing season — April through September. The fresh sap oozing from the wound is more likely to draw the insect that transmits that disease.
Tree companies like to prune in the fall months because the weather is nice, and a few additional customers helps with the all-important cash flow. I think whether you prune in the fall or late winter should be a case-by-case decision based on the needs of the tree.
Dead, broken or hazardous limbs should be removed anytime. If the pruning job is for this reason then anytime would be okay. Removal of major limbs or structural pruning is best left to late winter.
Shrub pruning is a different beast all together, as we prune them based on their flowering habit. Early spring blooming shrubs are pruned just after bloom, while the summer flowering types are best pruned just before growth begins in the spring. Fall pruning is not recommended.
Roses, here again, are altogether different. The majority of roses in the landscape are the easy or low care shrub roses such as Knock Out. Keep in mind; these are really treated like a shrub not a fussy hybrid tea rose. Pruning roses in the fall is not recommended as the wound created by the cut can result in additional or more severe winterkill of the cane. Basically, leave the roses alone in the fall. Pruning of roses is best accomplished in late March or early April after the chances of all hard late freezes is past.
Fall is a great season in the garden with the changing of the season, but for most plants it is best to leave the saws and clippers in storage until late winter.