Tired of snow? Ready to use Punxsutawney Phil for target practice? The snow we have had this winter isn’t all bad. Actually, it has been protecting your plants when the temperatures drop into the single digits and below.
A blanket of snow acts and insulation and the deeper it is the more protection it provides. Newly fallen snow is approximately 90 to 95 percent trapped air. Since that air is unable to circulate the heat transfer from the ground to the air is inhibited. Surface soil temperature is increased by two degrees for every inch of snow. According to David Hansen, a University of Delaware Cooperative Extension soil and environmental quality scientist, a study done at minus 14 degree F found that the soil temperature under 9 inches of snow was 28 degrees F. That is a huge difference between soil and air temperature!
This insulation can keep the soil from freezing to greater depths. The depth to which the soil freezes can be crucial especially to evergreens. If sunlight raises the ambient air temperature in the daytime evergreens will lose water. With the ground frozen to below the level of their roots they are unable to take up water to replace that which is lost and can die as a result.
The snow blanket will also keep the surface soil from thawing when the temperature rises during daylight hours or on sunny days. Freezing and thawing of the soil results in the heaving of plant roots and bulbs. Once the roots or bulbs are out of the soil they will freeze with the next cold cycle.
The snow provides water for dormant shrubs that continue to lose moisture through their branches in the winter. It is particularly crucial to evergreens, which do not go dormant and need a certain amount of water throughout the winter to survive.
The snow also provides a supply of water for the coming growing season. Five inches of a heavy snow will melt into one inch of water. It may take as much as 15 inches of a fluffy snow to provide an equivalent amount. If the snow melts quickly it runs off and can cause flooding but a nice slow melt seeps into the ground.
Don’t hate the snow. It may be your plant’s best friend.