Ask a Master Gardener: Protect evergreens from wind, sun
Wintry conditions can cause evergreens to turn brown.
Q: I see that some people in my neighborhood have wrapped their evergreen trees with burlap. I put in some arborvitae shrubs last summer. Should I be wrapping them with burlap now? What is the reason for the wrapping?
A: The wrap is intended to protect the evergreens from winter injury. Wintry conditions can cause evergreens to turn brown. Arborvitae are particularly prone to this problem, so, yes, you may want to consider protecting yours, too.
The forces assaulting our trees and shrubs in winter are cold, wind and sun. Sun can warm up the dark green foliage, which is then damaged when the sun disappears and the cold sets back in. Wind can dry out the foliage, and the frozen ground doesn’t contain any water the shrub can take up to replace that lost moisture.
Often the worst problems will be on one side of the tree, where sun or wind is fiercest, but it’s still a good idea to protect the whole tree.
Wrapping in burlap is a good idea, but leave the top open so that some light and air can reach the plant. The burlap may also help deter deer, which like to browse on arborvitae. And it may help protect branches from the weight of heavy snow. One master gardener offered an ingenious method for fastening the burlap: She uses gardener’s twine and a crochet hook.
Do not wrap evergreens in black plastic, which heats up too much in the sun.
If you decide to add more arborvitae to your landscape, it’s a good idea to think about placing them where they’ll have some protection from winter wind. Extension recommends planting them on the north or northeast side of the house.
Making sure they’ve been well-watered through the growing season — but not overwatered — can also help them weather the cold.
Written by U of M Extension Master Gardeners in St. Louis County. Send questions to firstname.lastname@example.org .