pruning outdoor evergreens

Asked November 5, 2019, 10:06 AM EST

I have a 15 foot tall Thuja Filiformis weeping threadleaf evergreen that appears to have been grafted. It was only supposed to grow to 8 feet. I would like to prune it dramatically to about six feet. When is the best time to do this? Can I prune it in the winter? Thanks.

Montgomery County Maryland

2 Responses

This tree is not going to tolerate such a severe pruning well. The rule of thumb is to not remove more than 1/4th of a tree at one time.

In addition, arborvitae will not grow new green shoots from "old wood", ie. brown-barked part that is not new this year. It has no buds that will break out new growth. It is not going to fill in new, close shoots to hide where it is pruned.

When and if you prune, prune back to a live, green side-shoot. Pruning should be done in early spring (March is generally good) so that new growth hides the empty areas best.

Here is our pruning page with links: https://extension.umd.edu/hgic/topics/pruning-tree-and-shrub-basics

Ellen


This tree is not going to tolerate such a severe pruning well. The rule of thumb is to not remove more than 1/4th of a tree at one time.

In addition, arborvitae will not grow new green shoots from "old wood", ie. brown-barked part that is not new this year. It has no buds that will break out new growth. It is not going to fill in new, close shoots to hide where it is pruned.

When and if you prune, prune back to a live, green side-shoot. Pruning should be done in early spring (March is generally good) so that new growth hides the empty areas best.

Here is our pruning page with links: https://extension.umd.edu/hgic/topics/pruning-tree-and-shrub-basics

Ellen