Winter produce is coming

Fresh, local produce is something people in the northern tier states normally say goodbye to about the same time the geese head south each fall. However, thanks to the hardy souls of Minnesota and the expertise of horticulturists at the University of Minnesota, fresh, local produce — in the dead of winter — is becoming more of a reality for both home gardeners and commercial growers.

People like Sue Wika and Tom Prieve, of Paradox Farms, and about a dozen other like-minded Minnesota farmers, are busy perfecting a passive solar greenhouse that is a practical and potentially profitable way of growing fresh greens and other crops for home consumption, local markets and Community Supported Agriculture.

“We built it for many reasons,” says Wika who, along with Prieve, is an educator for the Sustainable Farming Association. “It was really through our educational pursuits with our students that we decided we were going to put one up here. We’re all about teaching students farm skills and presenting them with opportunities for four season income streams, growing for themselves but doing so in a way that is responsible environmentally.”

This will be the third year Wika and Prieve have been growing crops in their deep winter greenhouse and the results are impressive. They’ve been able to successfully grow a variety of greens — kale, arugula, mustards — as well as Chinese cabbage and beets for themselves and friends. This winter they’re going to start a CSA and sell produce to surrounding neighbors.

“We have definitely broken even the first two years,” says Wika, who keeps detailed records of what they’ve grown and sold. “And I believe this year we’ll have a nice little profit.” She says some of this will be from direct sales and some from the fodder she grows and feeds her livestock, which she admits is a little more difficult to put a dollar figure on.

As one can imagine, fresh, local produce in winter is appealing to folks who would otherwise be eating produce shipped across the country. Local consumers have responded in kind and are willing to try some of the fresh greens they’re growing, some that Wika described as “edgy,” like arugula and pac choy. “I like it when I can have people over when it is 30 below out, our Chinese cabbages are getting big and people are like ‘oh my gosh.’ They’re just amazed that we can grow that in here.”

They’ve been guided in the building and operation of their deep winter greenhouse by the experience and expertise of Carol Ford and Chuck Waibel, who co-wrote the Northland Winter Greenhouse Manual She says in addition to reading the book, they’ve visited Ford’s greenhouse several times. Now they not only produce food but teach other people how to build these structures, using the Northland Winter Greenhouse Manual as their textbook. (Editor’s Note: for more information on Ford and Waibel, read Ford’s article in the April 2014 edition of Produce Grower.)

“We get requests every week (on how to build a deep winter greenhouse),” says Wika. “People are excited about the concept, we even get requests from the city, ‘could I put this off my restaurant,’ certainly you could, it would just have to be scale appropriate.”

Prieve, an experienced builder, constructed the 25-foot-long greenhouse on the side of their barn. It faces the southern sky at a 60-degree angle. Double paned polycarbonate panels let the precious winter light in and keeps the harsh elements out. The entire structure cost about $5000 in materials. As a passive solar greenhouse it relies on very little supplemental heating, even when the mercury dips well below zero, which it often does during a Minnesota winter. Instead, it can tap into stored heat.

As Prieve explains it, when the temperature in the greenhouse hits 80 degrees, tiny duct fans force warm air through black pipes located near the ceiling, the air then travels downward to perforated drain tile underneath the greenhouse. The heat is captured in the rocks located below the surface of the ground and is released upward during the night. The only time he uses supplemental heat, i.e., liquid propane, is when the temperature inside the greenhouse dips below 42 degrees. This winter he’ll pipe heat from a wood stove into the greenhouse as needed, further reducing energy costs.

The seeds for the various greens are started on heat mats inside the greenhouse. The greens and livestock fodder, including barley, are grown in a soiless media prepared by Wika, who is the principal greenhouse grower. The plants grow in planters made from rain gutters, with holes punched in the bottom for drainage. This setup allows growers to maximize space in the greenhouse. Produce can be harvested pretty quickly and another crop can be started.

In the early spring, Wika uses the deep winter greenhouse like a conventional greenhouse, starting seedlings, like tomatoes and peppers, that can be set in the field when they’re ready to transplant. In summer, she’ll use it as a large dehydrator to make sun-dried tomatoes.
 

Join the movement

Paradox Farms is part of a larger movement in western Minnesota and the Midwest in general to make more fresh produce available to locals or in broader terms, form a sustainable food basket.

“Not all people in rural areas have access to local food during the winter months, especially when the price of gasoline is high,” says Greg Schweser, Associate Director Local Foods and Sustainable Agriculture at the University of Minnesota. “If something were to happen we’d like to be able to bounce back,” he explains.

Schweser is working in conjunction with the Department of Horticulture at the University of Minnesota to help promote and lend growing expertise to would-be deep winter greenhouse farmers.

“A lot of people are interested in switching from bedding plant production to food,” says Schweser. “We’re looking at the production practices in terms of light, and humidity, find out what the optimal growing conditions are and asking if we should we use led lights. We’re also looking at nutritional values, how the produce in the greenhouses compare with grocery store produce.”

One thing that appears to be certain is there is a demand for fresh produce in the dead of winter.

“Basically, anyone that wants to put one up would have no problem selling their stuff,” says Schweser. “But if production was ramped up this would be something interesting to see, I’m not sure where demand and supply would meet.”

In their tenth year of production, Ford and her late husband, made a move to form the Deep Winter Producers Association to encourage more farmers to get into the game. They’ve had assistance in this endeavor by an award Waibel received before his death from the Bush Foundation Fellowship.

Ford views the deep winter greenhouse and the produce it supplies as a viable business model, albeit a niche market. She says niche markets make money in virtually all businesses, and this one should be no exception.

The challenges that lie ahead have more to do with the diminished light during the winter months, rather than lack of demand for the product or even the frigid Minnesota temperatures. Schweser says supplemental lighting may be prohibitive due to costs, but it is something worth looking into.

Neil Moran is a horticulturist and freelance writer in Sault Ste. Marie, Mich.

For more information:
Deep winter greenhouse workshop: On January 31, 2015, from 10:30 a.m. until 3:30 p.m., Paradox Farms will be hosting a workshop, titled: Deep Winter Production of Greens and Livestock Fodder Utilizing Passive Solar Energy at their farm near Ashby, Minnesota. For more information on attending visit: www.sfa-mn.org/farmskills101/.

Construction plans and other detailed information on deep winter greenhouses: "Cold-Climate Greenhouse Resource Manual: A guidebook for designing and building a cold-climate greenhouse" (University of Minnesota Extension).