Tuck landscapes in for winter
After they've entered winter dormancy, most High Plains landscape plants can benefit from mulching. The covering will conserve moisture. It also will lock in the cold to protect plants from winter's upcoming freeze-thaw cycles.
"Those cycles can literally heave shallow-rooted plants out of the ground. That's why winter mulch is particularly important for garden mums and strawberry plants," said Ward Upham, horticulturist with Kansas State University Research and Extension.
In Kansas, freeze-thaw cycles kill more plants than the state's occasional sub-zero temperatures, he said.
Mulch used to conserve moisture of trees and shrubs must not directly contact woody trunks, however. Trunks need a "doughnut hole" of space several inches wide on all sides. The only exception is hybrid tea roses, which need a mound of mulch and/or soil to insulate their graft.
"You'll need to check the protected plants periodically, because mice and voles sometimes use mulch as a winter cover. Plus, they tend to view tender bark as winter food and sometimes will girdle and kill a woody plant," Upham said. "Rabbits and mice also will climb on top of snow-covered mulch to gnaw on branches."
That's why a good practice is to protect young and/or fruiting trees and shrubs with a trunk-enclosing cylinder of plastic wrap, poultry wire or hardware cloth. The cylinder must extend several inches into the ground and, if possible, about 18 inches above ground without touching the trunk, he said.
"You can check for mice by baiting a mouse trap with peanut butter and placing it far enough inside a plastic pipe that pets can't reach it. Put the pipe near vulnerable plants and reset it about once a week," Upham said.
Broad- and narrow-leaf evergreens may need the additional protection of a burlap wrap, the horticulturist warned. Rhododendrons and blue spruces, for example, can be subject to winterburn from exposure to strong winter winds and/or salt burn from being too near a treated road.
"Any evergreen also can be at risk to winterburn if it didn't get enough moisture during the growing season or it doesn't get supplemental moisture during a dry winter," he said. "Because evergreens don't lose leaves, they also don't stop losing water from those leaves and sometimes need watering when temperatures are above freezing."