It turns out most tree and shrub damage in winter is not cold-related. Animal damage is the most common culprit.
Winterizing fragile trees and shrubs is a simple and prudent exercise in landscape management. Mulching and watering before the ground freezes up can save you a bundle of time and money.
“As long as the soil drains well, water the trees through autumn at least once a week unless there is a lot of rainfall,” said Gary Johnson, an Extension professor with the Department of Forest Resources at the University of Minnesota. “Soil moisture should be to a depth of 8 to 12 inches for the roots to take up water.”
Apply insulating mulch but don’t overdo it. Piling mulch volcano-style against a tree trunk is the same as burying a tree too deep, Johnson said.
Most tree and shrub damage in winter is not cold-related, he said.
“Animal damage is the most common,” he said, recommending protective fencing around trees if deer are a problem, “or at least stem protectors like hardware cloth or plastic protectors.” And then there are the troublesome bark- and root-eating squirrels, rabbits and voles. Tree guards and chicken wire generally are used to keep them away.
Burlap and straw wrappings help insulate the small trees and evergreen shrubs typically used in foundation settings. “But with straw, take care not to make it a wonderful condominium for rabbits and voles,” Johnson said.
The food supply quickly dwindles for wildlife after frost sets in, and most eventually go looking for food, said Ken Lane, chief marketing officer for Stark Bro’s Nurseries & Orchards Co. in Louisiana, Missouri.
“Even squirrels, who ‘squirrel away’ acorns for the winter, may prefer young tree bark for a change of pace,” he said.
Small trees being grown in containers need to be moved somewhere where their roots won’t freeze but where they can still stay dormant, said Rhonda Ferree, an Extension educator with the University of Illinois.
Temperatures should be kept in the upper 30s or lower 40s, and gardeners must make sure the containerized trees don’t dry out in winter.
“Maybe a cool basement or garage,” Ferree said. “Or bury the container in the ground or with mulch.”
Nurserymen often “mulch-in” container plants in winter by laying them against each other and packing the container area with mulch, she said.
Fall is the best time of year to plant trees — just don’t plant them too late.
“If they are planted well before the soil freezes, they should have time to put out new roots, which will get them through the winter and a jump start on spring,” Ferree said.
Planting in the right location is also important for wintertime tree protection, Minnesota’s Johnson said.
“For evergreens, southern and southwestern exposures are tough, especially if the plants are backed by a light-colored building,” he said. “The sun warms them up in the winter, the needles lose moisture that is difficult to replace, and the plants are scorched and browned by spring.”
Marginally cold-hardy plants can survive if placed in spots protected from wind and cold-pocket frost damage.
“Focus on protecting plants from the winter winds and low-angle winter sun,” Johnson said.