What Is the Best Way to Trim Back Arborvitae?

Spring Pruning

• Prune arborvitae in the spring by trimming individual branches with hedge clippers. Prune back to an upward growing side branch to encourage healthy, new growth. Do minor trimming as needed throughout the summer, trimming a few inches only from each branch.

Shearing

• Although shearing is fast and convenient, it rarely creates an attractive arborvitae. Shearing encourages fast growth along the outer branches of the tree, which in turn shades the interior. Eventually, the interior will die out, creating a hollow space. These trees are more prone to browning in winter, plus insect and disease problems.

Shape

• When pruning an arborvitae, make sure that the top of the tree is narrower than the bottom. Many homeowners prune the trees so the top is wider, which shades the lower portion of the tree, eventually causing bare spots to form. Many arborvitae have a natural, pyramidal shape, which lends itself to correct pruning. Prune rounded arborvitae plants so the top is slightly smaller than the bottom.

Size

• Arborvitae almost always start out as compact nursery plants, but many varieties eventually grow 30 to 50 feet high. Read plant labels carefully and select an arborvitae that will fit the space when it's mature. Pruning an arborvitae back to its control size is very difficult. Cuts made into bare wood will never grow again, leaving bare spots in the arborvitae. Prune only the branches with fresh growth to control the size, trimming them back 3 to 4 inches each season. Remove arborvitae trees that are too large for their spaces and replace them with a more suitable variety.