Q. Last November my next door neighbor’s African sumac trees were pruned to a trunk and branches. They were cut back so much I was sure they were being removed but was told they would leaf again. They did and are green and a lovely, smaller shape. I am planning to take the plunge with my tree but was advised to wait until February to avoid freezing damage. What should I do?
A. I will get to the February pruning. There is a right way and wrong way to radically prune large trees to a much smaller size. African sumac trees will survive this kind of pruning and you can get a much smaller tree. But the resulting growth from this tree will be weakly attached to the main trunk and large branches. This results in a lot of future wind damage to the tree and will cost more money to have this repaired later.
Radical pruning that dramatically reduces the size of a tree must always be done during the winter months. Winter freezing damage to this tree does not happen very often here so I am not overly concerned about waiting until February. Not a bad idea though if the tree will look ugly until it regrows.
We are talking about African sumac now. This type of pruning will not work on all large trees. If this type of pruning had been done to most ash trees, it would’ve killed them.
The acceptable method for reducing the size of larger trees is a technique called “drop crotching”. This technique identifies the tallest limbs and removes them at a “crotch” in the tree, using a clean cut that leaves no stubs. When cutting trees in this way, the height is reduced but strong limbs remain to support the canopy and reduces future wind damage.
Basically, “drop crotching” can be done to any large tree, not just African sumac. The type of pruning you saw done to your neighbor’s trees only works on trees that sucker easily from larger limbs.
Dramatically reducing the size of trees by pruning is best left to tree care professionals, certified arborists, who have passed rigorous exams demonstrating that they understand and can practice highly specialized form of pruning correctly. They are more expensive but they know how to do it correctly.