By Dennis L. Patton
OLATHE, Kan. — Each fall our office receives a number of calls about pruning. The callers are really not asking a question, but are rather seeking permission. For some reason, people feel the need to prune in the fall.
Fall is not the time to prune trees
I am not sure where people get the idea that it’s okay to prune in the fall. Let me explain why fall pruning is not recommended.
Pruning is good for the overall health of the plant. We prune for a number of reasons, including: improved structure, flowering  and fruiting.
Pruning is part of an overall plant health maintenance program. It is important to remember that a pruning cut does result in an injury to the plant. Just like in humans, cut tissue is wounded and time is needed for it to heal. Fall pruning creates an open wound for a longer period of time.
Best time to prune trees is late winter
Ideally, we would like for the cut wound to heal (seal over) as rapidly as possible. An open wound can be the entry path for insects, disease, rot and decay. For this reason, pruning trees is best done in late winter. At this time of the year, the cut wound is created just before the season of active growth and the plant can start the repair process.
Pruning trees is species dependent
Some may recommend pruning in the fall because the likelihood of insects and disease affecting the tree over the winter months is extremely low. Depending on the species of tree, fall pruning would be better than summer pruning.
Oak trees are an 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 Sept. The fresh sap oozing from the wound is more likely to draw the insect that transmits that disease.
Why do tree companies prune in the fall?
Tree companies like to prune in the fall months because the weather is nice and the additional customers helps with their 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.
Exceptions to the pruning rule
Dead, broken or hazardous limbs can be removed any time of the year. If the pruning is for this reason then go ahead and schedule the job. But leave the removal of major limbs or structural pruning to late winter.
Pruning Shrubs
When should shrubs be pruned?
Shrub pruning is a different beast all together. They should be pruned based on their flowering habit:
• Early spring blooming shrubs are pruned just after they bloom.
• Summer flowering types are best pruned just before growth begins in the spring.
Fall pruning is not recommended.
Pruning Roses
Roses are different altogether. The majority of roses in the landscape are the easy or low care shrub roses such as ‘Knock Out.’ These should be treated just like a shrub, not a fussy hybrid tea rose. Pruning roses in the fall is not recommended because the wound created by the cut can result in additional or more severe winterkill of the cane. The bottom line is, leave the roses alone in the fall. Pruning of roses is best accomplished in mid-April after the chance of all hard late freezes is past.
Fall is a great time in the garden with the changing of the seasons. But for most plants, it is best to leave the saws, loppers and clippers in storage until late winter.
Dennis L. Patton, is the M.S., county horticulture agent, K-State Research and Extension/Johnson County