How Snow Can Protect And Damage Your Plants

Snow on your plants can be both protective and damaging. Snow is an insulator. Animals burrow down into it, when necessary, to protect themselves from frigid weather. It insulates because, well, snow is fluffy, sort of like a down jacket. As heat rises out of the warmer ground, it becomes trapped in the snow, slowing its release into the air. Snow has an R1 insulating factor. That’s not much. It’s slightly lower than bare wood and a far cry from the R35+ you’ll
want in your house. Still, if the snow is deep enough, it provides cold-temperature protection for plants. Researchers at Rutgers say 9 inches of snow can make a 42° F difference between the ground surface and the air. The deeper the snow, the more insulating it is. A loosely packed, deep blanket of snow can protect the ground from freezing, and freezing is tough on plant roots. (This doesn’t mean you should pile snow onto plants.

Dense, packed snow doesn’t have the fluffy-snow air pockets and therefore isn’t insulating. It can also break stems, branches and damage the dormant plants.) Snow-cover insulation can stop the ground from a hard freeze if the snow is deep enough. When the ground freezes, it swells, and the swelling can push roots out of the ground, which subjects them to the harsh winter weather.

To protect your plants from winter’s potentially damaging freezes, add three inches of mulch around the plants, without covering the stems. Even if the frozen ground does move the roots up a bit, the mulch will help protect the roots.

If you didn’t get around to adding mulch last fall, go ahead and add it when you see the bare ground and/or bare roots (don’t go digging for the roots; you’ll cause more harm than good). If you do see roots, try to push them back into the soil gently and add mulch. Note: The newly planted stock is most vulnerable to the root-damaging freeze-thaw cycles.