Winter is here. As you check the thermometer and look outside, rest assured all those brown, dry plants in the landscape are not dead. I think all gardeners fret about new plants or favorite plants once winter weather sets in. Will they survive? But like gamblers at the card table, we take our chances again and again. Indeed, some of your plants, for all the promises that come with labels and zone designations, may not make it through the winter. Why is that?
The one thing plants need most of all is adequate moisture. Anyone who gardens in the Santa Fe area knows all too well the challenge that phrase presents. For those of us who began our gardening endeavors in locations with more warmth, rain, or snow, it’s vital to grasp this concept as you garden in our arid terrain. We are advised to water a few times during the winter months, especially new plantings, when temperatures get above freezing. But how many of us do it?
There’s good reason to water in winter. Most cold damage comes not from the cold itself, but from drought. Hopefully you watered one last time before the freezes started. Even better is a layer of mulch to regulate soil temperatures. Mulch helps keep the worst cold from making it to the roots of your plants and protects them from the warming and freezing that goes on during the months ahead. Sudden, shifting temperatures in the soil can break roots or even push them too far out of the ground to be spared from the cold.
But what if you didn’t get mulch down before the cold set in? Snow is a great mulch. Julie Janoski, who manages a plant clinic at the Morton Arboretum in the suburbs of Chicago, claims that a layer of snow will safeguard the roots of trees, shrubs, and perennials and provide moisture when it melts. Moisture in plant cells gives them elasticity and resilience to freezing. Janoski also urges us to let snow remain on branches rather than brushing it off. Very cold branches are brittle and can break. “Go for a brisk winter walk outside and let your shrubs recover by themselves,” she advises. Roger Swain, author of The Practical Gardener, suggests that when a snowfall requires some shoveling, throw that snow around your shrubs and trees for extra protection.
While our deciduous trees and shrubs are dormant by now, their roots are still active. They are storing nutrients the plants will use to leaf out once the soil warms and the days lengthen, their cue to start pushing out new growth to grace your garden for another season. It’s best to leave the above-ground growth of perennials in place over the winter so that it can catch the snow and hold it around the plant to insulate it. If you didn’t do this, your cold-hardy plants will likely survive anyway, unless their root system is too small and gets too dry. You can tuck this advice away for next year.
One approach to your landscape that may spare you anxiety is to plant more native plants. Natives have deeper root systems, allowing them to reach below the freezing temperatures. We don’t know what this winter will bring, but some predictions are for warmer temperatures and less precipitation. So keep an eye on the thermometer. When it’s above freezing and there’s no snow on the ground, give your trees, shrubs, and new plantings some water at least monthly. Do it early in the day so the water can sink in before temperatures drop. If we get our typical burst of warmer weather in February, this is the perfect time to provide this vital boost to the health of our plants. They’ll thank you for it when spring finally arrives.
Laurie McGrath is an Emeritus Master Gardener and has volunteered with the NMSU Extension in Santa Fe County for over 20 years. She is a founding member of the Santa Fe Native Plant Project (SNaPP).