A (extended season) light at the end of the tunnel

Land Stewardship Letter
February 25, 2009
By Tom Taylor

Email this page

Tomatoes by the end of June and early July, with harvest continuing until September and October. On top of that, get three times the production. You may think these are simple boasts from a growing area far to the south of the Upper Midwest, or a prediction of the future when global warming has struck big time. In reality, those words are from vegetable growers right here in Minnesota. I heard such descriptions during the Minnesota Statewide High Tunnel Conference in Alexandria in early December. The University of Minnesota, USDA North Central Sustainable Agriculture Research and Education program, the Regional Sustainable Development Partnerships and the Minnesota Department of Agriculture sponsored this event. This was the first Minnesota-wide high tunnel conference, and judging from the interest and activity, it is about time.

While sometimes called a "poor person's greenhouse," high tunnels are not greenhouses. By definition a high tunnel is "a non-permanent structure that has no electrical service, no automated ventilation and no heating system." Some artificial heat is used in emergencies when the temperature drops. Plants in high tunnels do not use planters or growing boxes; instead the crops are planted directly into the soil. While many high tunnels are assembled from special ordered or found materials, many presenters mentioned the availability of kits from places like Farm Tek. These are covered with a four-millimeter plastic sheeting that on average lasts three to four years.

High tunnels allow for not only an extended growing season and reduced plant cull rate, but also hold the promise of production of crops not normally grown in Minnesota, all with little to no pesticide used.

The U of M has been involved in high tunnel research since 2005. One of the high tunnels being used at the Northwest Research and Outreach Center in Crookston has been certified for organic production. Their 2007 and 2008 research shows that "organic production in high tunnels works well and can be very profitable if certain production practices are followed and high nutrient levels are maintained and supplied," according to a summary of the research.

Today there is also research going on at U of M research centers in Morris, Lamberton, Grand Rapids, Staples, Waseca, the Twin Cities and Bagley/Bemidji. With high tunnel research being so new in the Upper Midwest, everyone is learning together. The U of M is working with 21 farmers as "grower cooperators" to help collect data on high tunnel production. There are an estimated 300 high tunnels currently in use in the state.

While most research seems to be focused on tomatoes and cucumbers, raspberries are also grown in high tunnels. Promising garlic research conducted at Crookston shows that the soil does not freeze much below 2.5 inches in high tunnels, making for much less loss to freezing when over-wintering growing bulbs.

Commercially the biggest user of high tunnels in the U.S. is probably Driscoll's Berries, with all of their berries grown in high tunnels. High tunnels are producing flowers in Kansas and melons in Missouri. There was even some interesting talk at the conference about growing dwarf tree species such as peaches in high tunnels.

While extending the season, garnering greater yields and growing crops not normally available here are all exciting prospects, high tunnels are not without their challenges. On several occasions during the conference, growing in high tunnels was compared to dairy farming because of the need to be so hands-on "all the time." That passive solar energy captured by the plastic can rapidly climb to over 130 degrees Fahrenheit in a short amount of time, necessitating venting. Moisture levels and soil fertility must also be routinely monitored. And because of the elevated heat, pollination can be negatively affected in a high tunnel system.

A farmer in northwest Minnesota has pushed the definition and functionality of high tunnels by building one that uses a Minnesota-made solar collector to heat the soil. This innovative expansion of the high tunnel design was built just this past summer and is being tested by a real Minnesota winter as you read this.

High tunnel research in Waseca involves red cabbage and ginger to produce elevated levels of anti-cancer properties. This fascinating research involves increasing these desired properties through light manipulation in high tunnels.

Use of high tunnels in the Upper Midwest is really just beginning. At the Minnesota Statewide High Tunnel Conference, it was refreshing to see the farmers and U of M researchers working together with a "we're learning from each other" attitude. It was an active example of a land grant institution and citizens teaming up. The results of these activities will not only be good for farms and rural communities, but eaters who appreciate an extension of their fresh produce season.

Tom Taylor, an organizer with the Land Stewardship Project's Community Based Food Systems and Economic Development Program, is based in Montevideo, Minn. He can be reached at 320-269-2105 or ttaylor@landstewardshipproject.org.

Originally published in the Winter 2009 Land Stewardship Letter, www.landstewardshipproject.org.

NOTICE: In accordance with Title 17 U.S.C. Section 107, this material is distributed without profit to those who have expressed a prior interest in receiving this information for research and educational purposes.

Above graphic: Detail from Minnesota State Fair poster, c. 1920. Courtesy Minnesota Historical Society.