While contemplating how quickly the days might pass by until I can board a plane and soar to a warmer place, a thought popped into my head. I wonder if the temperature under a layer of snow is warmer than it is in the open air?
What!? The two are related!
We who live in the frozen tundra throughout the winter months give these things some thought. We have precious perennials that have to get through the winter and sometimes it's as tough on them as it is us.
I live and garden in USDA Hardiness Zone 5b, which means (among other things) that perennials have a good chance of surviving temperatures of -15°F to -10°F. That's air temperature, not wind chill. Plants, unlike humans and animals, are not affected by wind chill, although the winds themselves can be damaging to woody plants.
Just outside our family room window, on the south side of the house, we have a microclimate. I'm convinced that it's a full zone warmer there than any other location on our property. It gets the warmth of a southern exposure to the sun, as well as being mostly protected from strong winds by a row of yews that run diagonally from the corner of the house to the southeast.
This fall, I planted some marginal plants in this area, in an experiment in trying to see if they would winter over. Coreopsis 'Limerock Dream' (Coreopsis, Zones 6-9) and Mexican Feather Grass (Stipa tenuissima, Zones 7-10) are there, as well as a young Maypop (Passiflora incarnata, Zones 6-10). The Maypop was shared with me from a fellow garden blogger, Kathy at Tangled Branches.
That was an experiment in itself, yet to give results. May will tell the story. But what about this -20°F stuff we had a couple of days ago? That's well below the limit of Zone 5.
As the snow came down earlier this week, I was happy to see it. Snow is a great insulator for these plants we grow and love. Without it, only the strong survive the coldest temperatures. With most perennials, we're concerned mainly with the root structure and the crown of the plant, not with what may be left standing up in the air.
There's warmth in the ground and we want it to stay there. Mulch helps. And so does snow. Think of it like bubble wrap. The pockets of air in snow are what help prevent the warmth from escaping the ground. Snow is a good thing.
Now, back to what I wanted to know in the first place, and the reason for this blog post. Is the temperature down under the blanket of snow warmer than the air temperature? I put the thermometer down in the snow as far as I could and left it in place for about thirty minutes. The thermometer outside read -5°F.