Why lack of snow can damage landscaping

Lack of snow can have damaging effects on landscape plants.

Snow is a mixture of air and ice and has low thermal conductivity compared to pure ice and soil. It is a natural insulator of the soil and buffers against low and fluctuating air temperature. While it’s been nice to avoid clearing sidewalks and driving through snowstorms, when we have very cold weather, it is better to have snow come along with it.

Snow cover keeps soil warmer

Snow cover provides insulation from the extreme cold. While most of our perennials can survive without any snow cover, they will do better if protected, especially those that are growing at the margins of their cold tolerance. While there are many factors, soil under snow is typically just below freezing (32 degrees Fahrenheit) all winter, even when air temperatures drop into negative digits. Without the insulating effect of snow, the frost layer will be driven deeper into the soil profile.

Snow cover minimizes the freeze/thaw cycle

The freezing and thawing of unprotected soil can easily damage shallow roots. Snow moderates the soil temperatures, minimizing the freeze-thaw cycle. The snow also protects the crown of the plant from damage through the expansion and contraction of soil and moisture.

Snow cover prevents desiccation

Soil is prone to drying out, even if it’s frozen, when nothing is covering it. The effects of sunlight, wind and sublimation (solid ice going to water vapor) are all greater on bare soil. Perennial plants with dry roots get colder and freeze harder. Plants wintering in containers are particularly susceptible. While at a much slower rate, evergreen species still photosynthesize during the winter months and must have moisture for this. Without snow cover soils will lose more moisture and increase stress on evergreens.

So, what do you do when Mother Nature doesn’t cooperate? On a large scale we’re at her mercy. However, if you have known cold-sensitive plants, newly planted perennials, or any plants you are particularly passionate about, you can help them by adding a 3-4 inch layer of wood mulch, straw or leaves above their root system. Tomato cages can be added, wrapped in burlap, and filled with straw or leaves to protect above ground portions of plants. These must be removed in the spring. Loose materials that will better insulate than those packed down.