This winter’s epic storms lavished near-record amounts of snow on a vast swathe of the American landscape. At my farm here in Bucks County, PA, five feet of snow have fallen since Thanksgiving, leaving the ground covered with a snowy mantle several feet deep.
Increasingly I hear friends and colleagues complain of “snow fatigue.” They want to see this vast snowy carpet rolled up once and for all—and a speedy ending to this prolonged winter’s tale. While I’m tempted to suggest they regard the great American Snow Pile-up from the overwintering plant’s point of view, I fear the answer would be a cannonade of hard-packed snowballs.
Veteran gardeners know a lush snow cover promises a bountiful garden season ahead. The current feet-deep snow blanket on the ground is a godsend for wintering plants: the thicker the covering and the longer the duration the better. Paradoxically, the same weather gyrations that dump all this snow provide the needed “security blanket” to protect overwintering plants and the soil from zigzagging temperatures and climate effects.
A few feet of snow provides an “igloo effect” that insulates the plants’ earthly home, shielding vulnerable root systems from potentially destructive temperature jumps. The frost heaves caused by winter’s “bipolar” temperature swings that lay waste to asphalt roads can devastate fragile soil. Left unprotected, plants’ root systems—subterranean habitat under siege, tissues torn and exposed to frigid air and desiccating wind—are doomed.
Deep snow cover actually helps warm “hibernating” plants. In winter, dormant plants, though asleep, are still in a minimal growth phase. A thick snow mantle warms the soil, plants’ root crowns and, in some species, the upper root system. Under the snow covering, the soil can be 25 degrees warmer than the air temperature. Without this snow security blanket, very low temperatures cause plants to suspend growth activity and utilize the stored energy in plant tissue to keep warm.
Sunlight boosts the thick snow’s warming effect, helping the soil retain the daytime temperatures into night. Snow helps conduct light to the soil it covers so plentifully. Under the thick snow layer, plants’ root systems engage in photosynthesis, powered by the sunlight, distributed evenly as if by an advanced lighting system. Nurtured in the light and relative warmth of snow’s cold greenhouse, plants will emerge earlier, grow lusher, and taller.
Finally, our winter’s thick snow cover creates a finely calibrated “drip system” that keeps plant roots underground optimally watered, even in frigid conditions. The warmest snow, drawing heat from below as well as above, nourishes the dormant plants. And come warmer weather—it will come, it will come!—the resulting snow melt will help keep water tables well-supplied, the better to slake the thirst of plants and trees.
Adopting the plant’s point of view cures “snow-blindness,” and opens our eyes to snowfall’s role as the white stuff with right stuff: an invaluable source of protection, warmth, light and moisture for plants. The snow may be white, but its rewards are green.