Arborvitae are easy-to-care-for shrubs or small trees that often can be seen as hedges in the home landscape. They are evergreen and have scale-type leaves with fine texture. Arborvitae have long, slender branches that grow in an upswept manner and can become severely damaged with the weight of snow. They are also susceptible to winter discoloration from water loss and sun exposure. Winterizing and correct siting of the plants prevent or minimize these damages.
One way to minimize the physical affects of a heavy snow is to tie up the trees. If the arborvitae are in a hedge, it is helpful to tie them together lightly to allow the structures to support each other. Individual trees can be wrapped with a herringbone pattern of twine to hold in smaller branches and prevent splaying or breakage. The center leader of the plant should be used as a support post and outside growth tied onto it. Remove the ties in spring to allow for free growth and to prevent girdling the wood.
Siting and Wrapping
Place sensitive plants such as arborvitae under eaves to prevent the buildup of heavy snows. Arborvitae are best planted on a west or north side to prevent winter sun scald. Wrap the entire plant except the top with a piece of burlap to protect the leaves from the cold and avoid winter die-back. Leave the top fourth of the plant open so it can collect sunlight for energy. Remove the wrapping as soon as all danger of snow has passed. Move potted plants under cover or indoors if possible.
Wait until all danger of frost or snow has passed before pruning the damage from the tree. Smaller branches that have been damaged can be trimmed back to the next set of healthy growth. Large-scale damage can also be removed, but it will leave a lopsided plant that will take many seasons to grow out. It is best to replace any heavily damaged plants if they are just standard landscape cultivars. Arborvitae can be pruned in August to remove suspect branches that might experience snow damage. Don't prune in fall because it could encourage new growth that would not have time to harden before the freeze.
Heavy snows also cause an arborvitae to list or slant to one side. In this case, you can install a tree stake and sling to gradually pull it upright again. Use a mallet to hammer in the stake just outside the root zone so you don't damage the roots. Purchase a sling, and wrap it around the stake and the central leader of the plant. Cinch the sling just taut and secure it. Over the course of the next few months, gradually tighten the sling. It might take a couple of seasons, but you can straighten the tree again without forcing it and causing more damage.