cutting off the tops
Will it seriously damage my arborvitaes if I cut off the top 4 feet? Will it grow back ? I have 2 arborvitae that have been growing in large brick planters for about 15 years. They grow to about 11' high and are too tall for the area. Although I trim 6" - 12" off the tops every 3 - 4 years, they always grow back. I am considering taking off about 4' in late November so I won't have to trim them so often. Will it seriously damage them or kill them? Will that much ever grow back?
Charles County Maryland
You can "top" your arborvitae, but it may result in a bare spot at the top of the plant. The problem is that arborvitae don't regenerate new growth very well when you cut back so far that you're cutting into the bare, needleless wood toward the inside of the branches. Arborvitae shed the inner, older foliage as new growth continues toward the branch ends.
If you lop off several feet from the top of the plant, you will end up with a bare spot at the top. However, the bare spot will not be visible from the ground. Green growth around the perimeter should be enough to hide the bare top from the ground, and this branching probably will even grow up and around the bare top in a year or two, provided that you are careful not to cut back the perimeter branches to bare wood.
The best time to prune arborvitae is in the late winter or early spring. It is better to do regular, annual prunings of arborvitae if you need to control their size, instead of drastic pruning every few years. Do not prune more than 1/3rd of the plant.