Minnesota 'deep winter' greenhouse grows veggies year-round
Their plants survive largely on natural winter light. Fans force rising heat down into a rock storage area, part of a passive solar heating system that captures the day's warmth and releases it at night. On cold nights, a gas heater kicks in to help keep the temperature at 42 degrees. There are no banks of artificial lights.
It's a different kind of greenhouse, mixing technology and old school ingenuity to create an energy efficient winter farm. University of Minnesota researchers say the idea is starting to take off. About two dozen deep winter greenhouses can be found now in Minnesota. Many more are in the planning stages. A deep winter growing association will soon give winter gardeners a place to share what they're learning.
The small operations can be put up and run without spending a lot of money. Wika and Prieve's $5,000 winter greenhouse near Ashby is built like a lean-to against the south wall of the barn. Clear plastic panels cover the south wall, which is slanted at a 60 degree angle to best catch the midwinter sunlight. Next year a wood stove will help fight the overnight chill.
Dozens of 3-foot-long pieces of plastic roof gutter filled with soil hang from the ceiling. Rows of them are suspended from just above the floor to head high. Thick green vegetation spills over the sides.
On the floor are plastic bags of soil with holes cut in them. Chinese cabbage, turnips, radishes and beets sprout from the bags. The heated rocks under the floor keep them warm.
There are a lot of varieties that do very well in the winter with little care. Still, Wika spends about eight hours a week planting, watering and harvesting. "I'm in here more time than I'm working," says Wika, who holds a doctorate in sociology. "I always spend a lot of time just enjoying the sun and temperature. A lot of it is leisure and therapeutic."
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