One way to prune a tree is to top it, which means cutting the top of the crown perfectly flat. This is often done in an attempt to control a tree's height. Fortunately, there are ways to help a topped tree recover.
1. Allow Recovery Time
The worst time to trim a topped tree is right after the topping occurs. Time for recovery is needed, which for a tree means an entire cycle of growing seasons. A topped tree needs all the foliage it has left to gather the energy it needs to survive and recover during summer. Then the tree requires the winter and the following spring to form buds and produce the new growth needed for recovery. Rejuvenation pruning can then be done the following year in late winter or early spring.
2. Feed the Tree's Roots
The loss of the top part of the crown will cause stress for the tree, as those leaves were needed to absorb moisture, air, and energy from the sun. A bit of extra care for the roots is needed to ensure there are no other nutrition or water stresses affecting the tree. A soil test to determine nutrient needs can be done, or you can simply use a standard tree fertilizer. It's also a good idea to provide supplemental watering during dry periods.
3. Choose the Leader
One problem with topping is that multiple branches can begin to compete for leader, which is the central trunk within the crown. Having too many leaders weakens a tree so it is more prone to split or topple over. The main goal of the first tree trimming after topping is to select a new leader from the strong, nearly vertical branches growing near the crown's center. Any other upright branches will be trimmed back so only one leader remains.
4. Manage Waterspouts
Every remaining main lateral branch nub will likely send up weak, twiggy vertical branches as the tree attempts to fill in the missing top of the crown. These are called waterspouts. Any nearly vertical waterspouts are removed at their base, while those growing at a more lateral angle can remain. Usually, no more than two or three of these new branches are left per branch nub so that overcrowding won't be an issue.
5. Restorative Prune Annually
It can take a few years for a tree to recover from topping. During this period, it's important to schedule an annual restorative tree trimming in late winter or early spring so that the crown can continue to develop a healthy shape.
Contact a tree trimming service for more information.