Birch trees are highly desirable landscape trees because of their beautiful bark and graceful foliage. Unfortunately, they aren’t known for their long lifespan. You can improve their chances by pruning birch trees properly and taking advantage of the best time to prune birch trees.
Reasons for Cutting Back Birch Trees
There are several reasons for cutting back birch trees:
- Remove dead, diseased, and injured branches for the health of the tree.
- Branches that rub together offer entry points for insects and disease, so remove one of them.
- Branches that grow nearly straight up have weak attachments to the trunk. Take them down while they are small to prevent them from breaking off later on.
- Remove a branch that is too close to another branch. This is best done when the tree is young.
- Remove branches that are too close to the ground to make landscaping easier and allow comfortable use of the shade.
- You can remove any branch that detracts from the overall appearance of the tree.
When to Prune Birch Trees
Most landscapers prune trees just before they break dormancy in late winter or early spring, but this timing doesn’t work for birch trees. They bleed a heavy flow of sap if pruned when awakening from their winter rest, so the best time to prune birch trees is late summer or early autumn.
When you prune at the proper time, you not only avoid sap flows, but you also avoid the egg laying season for most insects that infest pruning wounds. These insects cause unsightly damage, and they can spread serious diseases. Birch tree borers are tree killers, and you should reduce the risk of attack by cutting after their early summer flying season whenever possible.
How to Prune a Birch Tree
There are several steps in pruning a birch tree. Take care of the easy stuff first by removing side shoots and suckers as necessary. Next, decide which branches to remove. Be as conservative as possible. Removing more than twenty-five percent of the canopy of a tree at one time weakens it and may be fatal. Never top a tree.
Remove branches less than 2 inches (5 cm.) in diameter as close as possible to the collar, or thickened area where the branch attaches to the trunk. Use one quick cut with long-handled pruners to remove the branch and then clean the pruning tool with a ten percent bleach solution or a household disinfectant before moving to another branch.
Larger branches are taken down with three cuts. Here’s the procedure:
- The Undercut – From the trunk of the tree, measure 18 inches (46 cm.) out along the branch. At the 18 inch (46 cm.) mark, make a cut one-third to one-half of the way through the branch beginning at the underside and working in an upward direction. This cut prevents the falling branch from stripping bark and wood from the tree as it falls.
- The Main Cut – Measure an inch or 2 (2.5-5 cm.) out from the undercut and cut the branch from the top downward. Cut all the way through as smoothly as possible.
- Tidying Up – The 18 to 20 inch (46-51 cm.) stub that remains is an unnecessary eyesore and can cause disease if it dies back. It will not regrow, so cut it off flush with the collar.