We prune trees to contain their growth and to stop insect and disease damage in their tracks. It is an excellent way to promote plant health and encourage new growth. But it’s important to realize that pruning trees changes the growth and form of the plant, and doing it incorrectly, can damage the tree.
It’s important to prune trees the right way. And, if you end up with an over-pruned tree, you need to know how to fix it. Unfortunately, the reality is that if it’s a badly over-pruned tree, you may not be able to fix it. Good pruning minimizes damage to growing trees. Bad pruning creates problems.
What happens if you over-prune a tree?
If you don’t know enough about pruning trees and you over-prune them, you can damage and even kill them. You might not even realize that you’ve over-pruned trees.
In an article on the basic principles of pruning woody plants, the University of Georgia Extension highlights the importance of proper pruning of trees, shrubs, and other woody plants. They say that it involves science and art.
It takes science to know how and when to prune trees for maximum benefit. It takes art to make the prune cuts correctly.
Of course, it also depends on your reason for pruning trees. Typically, we prune trees to control their shape and size.
We prune hedge plants to a specific height and width to maintain function. And we often prune fruit trees quite low to the ground to make fruit picking easier.
Another important reason for tree pruning is to maintain plant health and improve the quality of stems, foliage, fruit, and flowers.
Douglas F. Welsh, professor and extension horticulturist from the Texas A&M University Extension in Texas, maintains that it’s better not to prune trees than to prune them incorrectly. He also emphasizes how important it is to use the right tools.
Apart from over-pruning, more trees are ruined or killed by people using a chain saw or pruning saw to chop off branches than those killed by pests and diseases. Continued improper pruning will damage and weaken the plants.
He and many other experts condemn the practice of topping trees. He refers to it as the Texas chain massacre!
When you prune you trim trees and hedges. When you top trees, you basically hack the top of the tree off.
Dangers of tree topping
The Illinois Department of Natural Resources Division of Forestry Resources has a short paper on tree topping that explains how bad this practice is.
In essence, topping, also known as heading or dehorning, is over-pruning at its worst!
The difference between a properly pruned tree and one that has been topped is easy to recognize. Properly pruned trees often look as if nothing has been done to them.
Correct tree pruning will reduce the size of the tree but retain its form and beauty. A topped tree will commonly look like an ugly stub.
Fast-growing water sprouts will shoot up from a topped tree. Instead of one new sprout growing to replace the vertical branch that has been removed, a whole bunch sprout.
The result is that they all compete to be the new vertical branch. In doing so, they compromise the structural integrity of the tree.
Properly pruned trees, on the other hand, will continue to grow naturally and more slowly. Your tree will look good and its size will be better controlled.
The irony is that if you don’t do something to fix your over-pruned tree, you’re going to end up with an even taller, bushier, probably unsightly tree. Also, tree wounds created by topping tend to expose the tree to decay as well as attack by insects or disease. When a tree is pruned correctly, the wounds heal a lot faster.
Because the tree has been over-pruned, it loses a lot of its foliage. This starves the tree, which, in turn, weakens its roots, reducing the structural strength of the tree.
Even if trees survive topping, their life span will be significantly reduced.
How to fix an over-pruned tree
It isn’t always possible to fix an over-pruned tree. But if it isn’t too bad, the tree will start to recover and continue to grow, and you will be able to fix it.
We mentioned water sprouts earlier. These are shoots that sprout from the branches or trunks of mature trees.
As the University of New Hampshire Extension explains, when trees are stressed they often produce the upright shoots we know as water sprouts. They generally grow from dormant buds in the bark and they aren’t firmly attached to the tree.
Topping and over-pruning are commonly the cause of water sprouts. But storm damage, disease, soil compaction, root loss, and drought can also cause them.
The warning is not to simply remove them otherwise they will grow back very quickly. You need to correct the underlying issue.
Rather remove some of them and then let the tree rebuild its energy reserves. Then, later, you can thin them so that they grow away from the tree trunk and form branches.
You can also shorten water sprouts to slow their growth and regeneration. Then, over time, you can prune the sprouts. This way they will develop into strong limbs that replace the weak limbs in the crown of the tree.
Will an over-pruned tree grow back?
Generally, over-pruned trees find it difficult to grow back to a healthy state. If the damage is severe, it may take a long time to grow.
Also, you may find that branches break off more easily because of heavy loads, including snow. Because they are more vulnerable to pests and diseases, an over-pruned tree may die long before it should.
How do you revive an over-pruned tree?
We’ve already said that it often isn’t possible to fix a tree that has been topped or over-pruned. But rather than just leaving it and hoping it will regrow into a healthy specimen, there are a few things that you can do.
The essentials are to ensure that you fertilize the tree regularly. You must also be sure to provide it with sufficient water.
Environmental Horticulture and Urban Forestry Advisor, Dr. Igor Lacan, summarizes the most important aspects of proper pruning in three points in an article he wrote for the University of California’s Green Bulletin.
- Prune small and prune often. Be sure to limit the total amount of branches you remove.
- Prune well. Make correct cuts, with clean tools. Also, be sure to dispose of pruned material appropriately.
- Respect the natural form of every tree you prune. Remember that we cannot make a round-headed redwood by pruning or a pole-like coast live oak without severely stressing the tree.
Ultimately, you should avoid any large-scale pruning. To quote the late Dr. Alex Shigo, who was a biologist and plant pathologist with the U.S. Forest Service during the late 20th century: “You cannot prune a big tree to make it a small healthy tree no matter how you try.”