topping an Arborvitae

Asked January 29, 2020, 2:21 PM EST

We live in Oceaside north of Netarts along the coast. We planted some Arborvitae as a screen. Unfortunately we didn't know deer love them and have eaten the middle of the trees. Dining is over for the deer as I have erected some deer fencing to protect the trees. My question is how to get the trees to fill in again. Would topping the trees force them to fill or do I have to replace them? If topping will work, is there a time of year that would be best?

Tillamook County Oregon

1 Response

Arborvitaes will retain their natural shape as they mature and regular pruning is usually not necessary. Arborvitaes will tolerate more frequent and heavier pruning if you want to shape them into formal hedges and topiaries. Follow these dos and don’ts to get the best results:

  • Do give arborvitaes a light pruning in early spring to keep them tidy and encourage thicker growth. Because new growth only develops from the leafy part of a branch, don’t cut back to bare wood.
  • Don’t lop off the top of an arborvitae to reduce its height. No new growth will occur once the branch tips have been sheared away, and you’ll end up with a permanent buzz cut. Instead, use selective pruning or thinning cuts to lower the height.
  • Do maintain the natural shape of your arborvitae and keep it wider at the bottom than the top. If you prune it into a V shape, you will shade the lower branches and the foliage may die back or become sparse.
  • Do remove dead or diseased branches immediately to prevent decay and allow new growth to fill in the gaps, pruning them off at the point where they leave the trunk.
  • Do remove accumulated dead foliage inside the plant annually or more frequently to improve air circulation and reduce chance of disease.

Here is a publication you may find useful:

https://www.arborday.org/trees/tips/

Hope this helps!