Is Snow Cover Good For Your Garden?

How a blanket of snow insulates your garden

Snow has a remarkable insulating effect. It protects dormant perennials, bulbs, and plant crowns from freezing and thawing cycles and thus keeps plants from dying over the winter. Without snow cover, the cells of many of your plants can freeze, and when they thaw, the plants may die. You’ve probably witnessed this when a frost appears unexpectedly late in spring and tender plants are quickly wiped out overnight.

Snow also insulates the soil and protects it from frost heave. When temperatures drop below freezing for an extended period, the soil freezes. To what depth it freezes depends upon the length of the cold streak. When it thaws, the soil may literally “heave” (swell upwards) which can snap root systems and dry out plants, causing extensive damage or death. Snow’s insulating properties mitigate freezing and frost heave.

The downside of snow on your plants

Of course, snow has its downside to garden plants as well, mostly from the weight that snaps thin branches (not to mention blizzard winds that may cause far worse damage).

After a snowfall, clear heavy snow from bushes and trees that might be damaged from the weight. I experienced this one year after a particularly hard winter when snow falling off of my roof smashed the branches of a shrub, leaving a gaping hole in the middle. In the spring I supported the shrub with clothesline and it eventually grew in to hide the damage.

Protect plants from winter drought with snow mulching

Did you know that your plants can experience a drought in the winter? Even though many plants are dormant, they still need water to survive.

Inspect shrubs and other perennials under the eaves of your house and other areas sheltered from snowfall. If the ground is snow-free compared to the adjacent areas, take some snow and fill it in around the base of the plant. This will insulate the crown and roots and will provide moisture as the snow melts. That’s called snow mulching. Don’t go overboard and pack too much around it, because you want to make sure that the melting snow easily drains away when the thaw comes.

Please note that you should avoid using snow from the edge of your driveway, street, or sidewalks for snow mulching. It may be contaminated with chemicals intended for melting ice. These products are typically very high in salt content and can quickly kill many plants.