Dealing with Broken Branches

Spring snow is full of moisture. That’s good news for winter-dehydrated landscape plants, but can cause problems for our trees and shrubs.

During late spring snow storms, the wet flakes cling to branches, causing them to bow under the weight. Sometimes branches will bend outward from the plant’s center. But if enough heavy snow accumulates, branches can break like matchsticks.

It’s obvious that broken branches need to be cut off, but what’s the best approach?

The best strategy is to remove the limbs in a way that gives the bark the best chance for sealing over the wound. You accomplish this through good pruning cuts. If the bark doesn’t seal over eventually, there’s an open pathway for decay organisms enter. They will rot out the center of your tree over time.

Here’s how you make a good pruning cut:

1. If possible, remove a branch all the way back to the place where it joins with another branch. Don’t cut in the middle of the branch, because the bark will never grow over the cut. The remaining stub will always be susceptible to decay. Shrub branches may need to be cut to the ground.

2. Don’t cut off the branch collar. The branch collar is a slight swelling around the base of a branch. Although it’s tempting to cut off the entire branch so it’s flush with the trunk, this type of cut removes the bark that will seal over the wound.

I’m pointing to the branch collar. Notice the thicker bark towards the base of the branch? Cut outside of the branch collar, or where it gets thinner and more orange-colored in this case.

3. Try to prevent the bark from ripping around the pruning cut. When people cut heavy branches, they often pull some of the bark off the trunk as the branch drops. This leaves another open area that will never seal. Instead, cut about 6 inches out from the final cut to remove the weight of the branch, then make the final cut. Your pruning cuts will seal over much better.

4. Be patient. It takes time for pruning cuts to seal. A one-inch diameter may take a growing season to seal over while larger cuts may take several years.

5. Don’t apply any pruning paint or wound dressing to your pruning cuts. Sealing over a cut can actually delay the bark from healing.

Be realistic about what you can tackle yourself. If the branches are higher than what you can comfortably prune, call a professional arborist for help. Look for an arborist certified by the International Society of Arboriculture. These tree care professionals have the training, experience and equipment to maximize your tree and shrubs’ long-term health.

For more information about making good pruning cuts, read Garden Note 612 by Colorado State University Extension, http://www.ext.colostate.edu/mg/Gardennotes/612.html. Here are some photos of good and not-so-good pruning cuts.

This is a recent pruning cut. Notice the bit of bark that ripped off at the bottom of the cut? This could have been avoided by cutting off most of the weight of the branch before making the final cut.

See how the bark ripped at the bottom of this pruning cut? The bark has never been able to seal over- and never will.

This is a good pruning cut because the bark is beginning to grow over the cut after a year or so. The branch collar was left intact.

Notice how the bark has been able to almost completely seal over this pruning cut. It will close eventually. This is ideal.

This warm my heart. A completely sealed over pruning cut. This is what we all hope for.