Can you imagine growing greens this gorgeous in the depths of a MN winter? (Zone 3-4)
In quantities big enough to provide for 18 families?
In a greenhouse that uses almost no supplemental heat?
and that is small enough to fit on the back of a garage? (18′ x 24′)
Well, that’s what the fine folks out at Garden Goddess in Milan, MN are doing. (they’ve just finished their 5th winter season). And they’ve written a book with all the details. And they were kind enough to let P and I come out to see “winter’s tastiest miracle” for ourselves.
Through “passive solar” technology, the greenhouse is heated from the bottom up. The sun passes through the poly, heats the air, the hot air rises and is collected in stove pipe that is blown 4′ down into perforated drain tile in a bed of gravel. The air rises through the gravel and the heat is collected in the rocks, providing the thermal mass that radiates heat back upwards when the greenhouse cools down at night or in cloudy weather.
Not only is it genius in theory, it actually works. By growing cool weather crops that can tolerate dips down into the 40s, they’re able to provide a winter CSA, even when outside temperatures drop below -30F. Although, during a string of sunny days in January, when snow is piled in huge drifts and the wind hollows outside, it can be 85F in the greenhouse!
I couldn’t believe it, so yesterday we drove 3 hours away to see it ourselves. I’m convinced. And if we can work out the financing, we’re hoping to build one of these in our backyard this summer to provide enough for ourselves and a small CSA.
Take that, winter!