How do you trim a hedge row of arborvitae?
I was wondering if you can tell me when and how to trim my hedge row of arborvitae? I need to cut off about six to eight feet off the height of this hedge row.
Arborvitae can be topped, but you do run the risk of leaving some dead spots on top and compromising overall plant health if too much is taken at once. I contacted the UMaine-Orono Superintendent of Horticultural Facilities, Mr. Brad Libby, to get his take on your question. He advised doing the pruning in late winter, close to early spring, to accommodate regrowth. Brad also thought 6-8′ would be quite a bit for the trees you have, and that he would recommend going more slowly and breaking up the topping back over 2-3 years to give the plants time to adjust.
Be aware, also, that the top of the arborvitae will not regrow once removed, so another reason to go slowly is not to drop it below the level you want. Read more about it in this Ask Extension Q&A.