Master Gardener - How to avoid common tree-pruning mistakes

Published: Sunday, February 2, 2014 at 07:21 PM.

Late winter (February – March) is the ideal time to prune ornamental trees. At this time, trees are dormant and have no leaves, making it easy to see branches. Done correctly, winter pruning creates a burst of growth in the spring—in all the right places.  On the flip side, bad pruning sets a tree up for failure. Here are some common pruning mistakes you’re likely to see in our area.

Topping: This is one of the ugliest and most damaging of tree pruning mistakes. Topping involves cutting away a large section of a tree's crown; for example, cutting all the branches across the top half of the tree. What you're left with is an ugly deformed specimen with a severely weakened branch structure. Topping happens a lot with crape myrtles (known as "crape murder") and other trees that have grown too large for the place they were planted. With crape myrtles, it's also done because people think it will result in more blooms. In case you were wondering, it won't.

Improper cuts:  A very common tree trimming mistake when removing branches is to cut them off too close, or flush, to the main trunk. By doing this, you remove the branch collar; an area of tissue with specialized cells that help the pruning wound to heal. You'll recognize it as a small swelling, or bump, right where the branch meets the trunk. The callous tissue that grows from the branch collar prevents disease from entering the trunk. When you remove the branch collar by cutting a branch off flush to the trunk, you're opening a wound that allows entry for diseases and pests, putting your tree on a path to an early demise.

Over-pruning:  No more than about 15% to 20% of a mature tree's limbs should ever be trimmed off at one time. In fact, 5%-10% is usually adequate. If a tree is already stressed, it should not be heavily pruned. When you remove too much of the canopy, you leave the tree unable to produce enough food, transfer nutrients, and structurally support itself.

People often over trim and thin their trees in hopes of getting the grass beneath to grow properly.  If you have multiple trees in an area where you'd rather grow turf, a better practice is to hire a tree care professional to remove selected trees to let in more light, and then perform structural pruning on the remaining trees so that you can have both healthy trees and turf.

Learn more

If you are concerned about the health and strength of trees on your property contact a certified arborist to assess the situation. Certified arborists are highly qualified tree professionals who have passed the certified arborist exam offered through the International Society of Arboriculture. A list of certified arborists practicing in North Carolina can be found on their website,, under the public outreach link.

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