Growing Green with Deep Winter Greenhouses in SE MN

In a nutshell it sucks warm air in at the top of the deep winter greenhouse (DWG) during the day and stores it in a rock bed so that at night when the weather cools down air is sucked in again and takes the warmth stored in the rock bed and heats the growing space.

One of our community members encouraged us to apply for the DWG 2.0 application with the U of M. We did and one of the criteria they were looking at was the ability to host groups to spread the work about DWG growing in Minnesota.

We give lots of mini-tours to visitors who come to our farm during our kombucha stand business hours and we also have student groups come to our farm. Last year we had almost 300 students get a tour of the DWG.

Learning how to grow through the different fall/winter/spring seasons with different amounts of light and heat. Keeping things growing when it is cloudy. It can get really hot in the growing space even in late fall and early spring so dealing with that.

We will be working with Dan Handeen, a U of M researcher to install a thermal curtain to help insulate the DWG in the evening.

Greg Schweser, RSDP Director for Statewide Sustainable Agriculture and Food Systems says the goal of the deep winter greenhouse program is “to develop a technology that is affordable for farmers to adopt and will allow them to profitably grow crops for market all winter long.” 

“Our intention with the deep winter greenhouse is to transform small and medium sized agriculture in Minnesota to create a full year-round local food system. Furthermore, by using a greenhouse that relies primarily on solar heat stored in an underground thermal mass, farmers will be able to grow market crops with minimal reliance on external heating sources which both reduces operational costs and limits carbon. Farmers that can pair crops grown in a deep winter greenhouse with crops stored in root cellars, will have the ability to offer a full variety of winter crops to their customers.” 

As more knowledge about deep winter greenhouses is gathered, RDSP encourages farmers during the colder months to plant crops that can survive with low light and colder temperatures to have a greater chance of germination and growth success. Schweser mentioned some of these plants could be Asian greens, lettuces, and some brassicas. He also knows of farmers who are experimenting with ginger, turmeric, and tropical fruits. While the full potential of deep winter greenhouses is still being studied, the hope of more food production and community engagement with local foods is something to look forward to, even in below freezing temperatures.