The Magic of Unheated Greenhouses

Photo by oldpatricka

The tenacity of New England winters never ceases to amaze me. Here in New Haven, March came in like an angry lion, dumping a foot of snow on my doorstep and on the Yale Farm.

It's at moments like these, when true spring seems eons away, that I give thanks for the greenhouses. The plastic-covered, unheated hoophouse at the farm is verdant and productive right now. A peek inside offers a carpet of green -- spinach, mizuna, arugula, peas.

We grow year-round both inside and outside the greenhouses. Underneath the snow, there are still carrots and parsnips in the ground -- they get sweeter with the frost. But those are indisputably winter vegetables, while the greenhouse greens herald spring.

Our greenhouses are simple things: a row of metal rods bent in the middle with their ends in the ground, making a line of half-circles about 12 feet tall. Every November, we wrestle a swath of greenhouse plastic over the metal ribs (which usually involves at least 20 volunteers and muttered prayers for the wind not to blow), pop plastic sides on the ends, and seed the covered greenhouse with greens like spinach, mizuna, arugula, mache, and claytonia.

The greenhouses aren't heated by anything but the sun, but each layer of covering effectively moves the covered area one and a half USDA zones to the south, which means that while the greenhouses are in Connecticut, the plants think they're in Virginia. Covering the plants with a layer of Reemay makes the seeds even cozier, and come February and March, we have salad greens. (For more information on season extension, you can turn to the guru who taught us: Eliot Coleman, brilliant Maine farmer and author of The New Organic Grower).

The magic of the unheated greenhouse makes it a unique teaching tool. When local third-graders or jaded college students peek beneath the Reemay, they respond with the same breathless enthusiasm. It's an excitement that doesn't fade with familiarity: Even as students learn more and more about winter growing, or see a few seasons at the farm, early-spring spinach still feels like a gift. If we're lucky March will go out like a lamb, but in the meantime, at least we have arugula.