How to protect your plants from winter cold
Suddenly, it’s winter, and we’re wrapping ourselves against the cold in puffy coats and fuzzy boots. What about our plants?
“The best way to protect our gardens in winter is to choose hardy, resilient plants in the first place,” said Julie Janoski, manager of the Plant Clinic at the Morton Arboretum. “There are ways to give vulnerable plants extra protection from some kinds of damage, but you can’t keep winter out of the garden.”
Here are some suggestions from the Plant Clinic for what to do — and what not to do — to protect plants.
Mulch well: An insulating layer of leaves or other plant matter over the surface of the soil will keep the soil consistently cool until spring. Plants will stay dormant and won’t be tempted to start growing prematurely in late-winter warm spells.
“The big danger to most plants in winter isn’t cold, it’s temperature swings,” said Sharon Yiesla, plant knowledge specialist. “It’ll be 20 degrees one day and 60 degrees the next. A brief thaw can bring plants out of their safe winter dormancy and make them start growing. Then they can freeze.”
Don’t wrap trees: It was once common to wind paper tree wrap around the trunks of young trees in the hope of keeping their tender bark from cracking in winter freeze-thaw cycles. The wrap can do more harm than good, Yiesla said, because it can trap moisture against the bark or attract damaging insects in late fall and early spring.
Shield against salt: Often, evergreen shrubs are brown and dead on the side that faces the road, driveway or sidewalk. The culprit? Salt used to melt snow and ice, which dries out plants’ tissues.
One way to protect shrubs is to erect a temporary fence to intercept the salt spray by stretching burlap between poles or steel fence posts on the side nearest the road. “Don’t wrap the entire plant in burlap,” said Janoski. “That would prevent air from circulating and let moisture build up.”
Surround tender shrubs: Chicago cold and wind can dry out shrubs that aren’t quite hardy here, such as bigleaf hydrangeas or tender roses. To protect them, avoid using plastic foam rose cones, which can cause damaging heat and moisture to build up around a plant. Instead, create an open, airy kind of insulation with a cylinder of chicken wire filled with leaves.
Let stalks stay: Rather than cutting back perennials, consider leaving the dried stalks and foliage standing. “They will insulate and protect the crown and the roots,” Janoski said. “It’s one of the ways that hardy plants naturally defend themselves against winter.”
For tree and plant advice, contact the Arboretum’s Plant Clinic (630-719-2424 or plantclinic@mortonarb .org).