Arborvitae Pruning - Ask Extension
I have arborvitae trees/bushes as a border for my yard. I have kept the sides pruned every year but have not prune the tops. As a result, they have ...
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Arborvitae Pruning #870163
Asked May 26, 2024, 2:41 PM EDT
I have arborvitae trees/bushes as a border for my yard. I have kept the sides pruned every year but have not prune the tops. As a result, they have grown to about 25 feet high and I would like to prune the tops. However, I do not want to take too much off the tops as it may harm them. What is a safe amount to prune of the tops? Thanks.
Montgomery County Maryland
Expert Response
No, unfortunately Arborvitae can't be topped or significantly reduced in height while retaining foliage on the cut stems. They are not capable of replacing lost foliage when branches are trimmed back to leafless wood (a normal state for inner, lower, or older branches), so any pruning that removes foliage will be permanent and might ruin the appearance of the plant, depending on your aesthetic expectations for the plants. If they are now too tall for their location, it would be simpler (granted, maybe more expensive at the start) to just replace them instead. There are multiple compact-growing Arborvitae cultivars on the market these days (some upright, some globe-shaped), plus other species options, depending on the site conditions. (Summer sun level, soil drainage, deer browsing risk, desired mature size, etc.)
Miri
Miri
Dear Miri,
Thank you for your response. I would like clarification on one issue. Does topping (cutting several feet off the top) damage the whole tree or does it just stunt growth at the top of the tree? The arborvitaes have gotten very tall so I would like to trim them a little shorter. If it just prevents the tops from growing again, I am ok with that. But if it is bad for the overall health of the tree then I would not do that.
Thanks.
Tom
Hello Tom,
It might not damage the whole tree, but it is more likely to stunt the top in the sense that regrowth is not expected. It depends on whether the pruning cut can seal-over without succumbing to wood decay that progresses down the trunk later, which will be hard to predict. (The cut wood should not be sealed with any type of tar or coating, as it needs to seal-over on its own.)
Miri
It might not damage the whole tree, but it is more likely to stunt the top in the sense that regrowth is not expected. It depends on whether the pruning cut can seal-over without succumbing to wood decay that progresses down the trunk later, which will be hard to predict. (The cut wood should not be sealed with any type of tar or coating, as it needs to seal-over on its own.)
Miri
