Deb Babcock: Protect plants from winter
October 2, 2011
Steamboat Springs — The hardiness of our garden plants depends upon nature and nurture. For instance, a blue spruce that grows in the mountains around Steamboat Springs is hardier than a blue spruce from the Cascade Mountains. Part of its hardiness is genetically controlled, and part of it is a learned response to our much harsher environment.
Plants that are native to our region typically survive our winters because they evolved in response to the climate and weather patterns of our mountains. Many of the plants in our gardens, however, were introduced from other climates or are considered exotic. They may not respond as well to our environment.
So what can a gardener do to protect outdoor plants and help non-native plants (or coddled natives, grown in greenhouses) develop survival defenses?
Outdoor plants kept in above-ground containers could be susceptible to frozen roots during a Steamboat winter. Consider moving these plants to a protected environment such as a cool garage or greenhouse or plant them in the ground or under a thick layer of sawdust or ground bark for winter.
Because we experience such intense sun in the winter, the needles of evergreen trees often heat up to 50 or 60 degrees during the day. This causes transpiration, or moisture to move to the surface of the needles. Because the ground is frozen, the roots are unable to replace water in the needles. Then when the sun goes down and the wind kicks up, frost and the ice crystals form and kill the needles. This sunscald often occurs on the south- and west-facing branches. You can protect your evergreens from sunscald with windbreaks, shading or commercial products designed to keep moisture in evergreen needles.
Sun and wind scald also can happen to the bark of trees with smooth or thin bark such as Aspens. For the first winter or two after transplant, consider wrapping the trunk from the ground to the first set of branches.
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Bark splitting and frost canker are two other problems caused by harsh winters. This often occurs when it gets cold at the surface of the soil and there is no protection for the plant by a covering of snow or mulch. Once it warms up, the dead bark splits from the tree, girdling it and preventing the plant from transporting water and nutrients from the soil to the leaves and branches. Eventually, the entire plant dies. Sometimes the dead bark sinks into the tree forming a canker. Protect your trees by mulching around the base but not right up against the tree base where small animals may nest for the winter and cause problems.
For other garden plants, help ensure their survival by making sure they don't go into winter with completely dry roots. Water one last time before the snow blankets the ground, and consider a layer of mulch to keep the moisture from evaporating in the sun and wind. The most tender bulbs and rooted plants should be carefully dug up and stored in a cool place such as the basement or garage until spring.
If your trees and plants can make it through a few Steamboat winters, they just might develop a hardiness comparable to our rugged natives.
Deb Babcock is a master gardener through the CSU Extension Routt County. Call 970-879-0825 with questions.