When you move into a new place, especially one with a large, mature landscape, the gardener in you will immediately start twitching if the plants on your lawn are overgrown. You may develop an irresistible urge to open the canopies and hard prune every plant you can reach — and some that belong to your neighbors. But, over pruning plants can be as bad, or even worse, than not pruning them at all.
Can You Kill a Plant From Over Pruning?
Although over pruned trees and shrubs don’t usually die if some part of the canopy remains, the damage from over pruning can be extensive. Over pruning reduces the foliage that’s available for making food for the rest of the plant and can allow pests and diseases access to the tree if cuts are made incorrectly. Plants may sprout excessively in response to so much canopy loss, both to protect the bark of the plant from sunscald and to increase food production.
Over time, continued over pruning may lead to branches that are too weak to tolerate wind or ice loads, or the plant may simply exhaust itself trying to replenish its canopy. The plant may become extremely weak, allowing a variety of pathogens and insects to invade. So, although pruning may not kill your plant directly, over pruned trees and shrubs can die as a long-term result of the associated stress.
How to Repair Over Pruning
Unfortunately, the damage from over pruning can’t be fixed, but you can help your tree overcome the many difficult days ahead. Provide proper fertilization and water to help your plant along; its diminished capacity for photosynthesis means that it’s more important than ever that your plant has all the building blocks it needs readily available for food production.
Wound dressing is rarely recommended, with only a few exceptions, such as when oak wilt disease is common in the area. In this case, wound dressing can prevent the penetration of vectoring beetles into healing tissues. Otherwise, leave wounds open. It is now believed that dressing wounds slows the natural healing process in bushes and trees.
Time is the only real cure for over pruning, so when you decide to prune, do so carefully. Remove no more than one-third of the canopy at a time, and resist the urge to top your trees. Topping is a practice that’s very bad for plants and may lead to brittle canopies.