Asked April 24, 2017, 10:19 AM EDT

I have at least 30 arborvitaes along the side of my property. They are now at least 30 feet or more tall and in good health. Except one is slightly leaning. I want to cut them to about 15 ft. Will this damage the plant? And if not, if cutting straight across, wiil this look funny when growing in the future? Also, how do I find someone to do this that knows about this plant?

Multnomah County Oregon

3 Responses

Unfortunately, most conifers including Arborvitae do not form buds on old wood, so if you remove the tops they will not be replaced. Arborvitae must be trained by pruning when they are young. If you remove the top of arborvitae trees you will have a permanent hole. If you want them to be 15 feet tall, the best thing would be to remove yours and replace them. The new, young trees can be pruned into a hedge or to the height you wish. Here is some information on pruning arborvitae from U. B.C. (Thuja occidentalis).

The best way to find an expert to help you with your trees is use a licensed arborist who has the training and expertise. Go to the International Society of Arborculture ( Click on 'Tree owner' find an arborist' in the box on the right side of the home page. Portland has several.

I appreciate your quick response, however, it will be cost prohibited by removing 30+ arborvitae trees that are over 30 ft tall. Plus buying more that are 10+ feet.

If I do cut them half way off, you said they wouldn't grow. That is not a concern. What I am concerned about is damaging the plant and also will the branches continue to grow up and then look funny. Would I have to have these trimmed to look more like a hedge? These plants are all along the side of my home and produce privacy.

If I keep them as is, I'm afraid some might toggle over. What are the chances?

Thank you for your reply. I certainly understand your concern. 30 30-foot tall arborvitae trees are a difficult situation. But picture cutting each of your trees in half. It's not an attractive picture. And they stay that way, they won't fill in. Topping trees is never a good idea. It structurally weakens trees significantly. Topping also opens up the tree to diseases. Coniferous trees don't put up new growth, and deciduous trees mount an overwhelming response with wild growth that is not structurally sound. My suggestion is to get ideas from a certified arborist. Perhaps you can remove some of the trees over time, a few each year. I would call 3 or more arborists and tell them about your situation and ask for their advice. Select the one that sounds reasonable and ask that person to come out to assess things in person.