By Ann Putnam
An “agitated public discussion or debate,” is one definition of “whoop-de-do” according Merriam Webster’s online dictionary. (Merriam Webster.) If you followed the recent approval of the Minneapolis Urban Agricultural plan you know there was a lot of “whoop-de do” about “hoop houses” or as they are sometimes called, “high tunnels.” Often the terms are used interchangeably but there is a distinction: a hoop house is made with two layers of polyethylene film and a high tunnel is made with one layer.
Growing plants in unheated structures is not new. It has been used in Europe for decades and is gaining popularity in the U. S. in northern climates. Elliot Coleman, an organic farmer in Maine, has been experimenting with hoop houses for decades and has written extensively about using them to prolong the growing season on his Zone 4 farm (Coleman. 1992.)
Above: High tunnels should be sited near a windbreak. A building immediately to the north protects the SOF high tunnel.
Since 2002 researchers at the University of Minnesota Extension have been studying high tunnels at the North Central Research and Outreach Center in Grand Rapids. They have also collected data from commercial growers using high tunnels in other parts of the state. (Nennich. 2008.) The research so far suggests several advantages to using high tunnels.
On the plus side, some crops grown in the warmer enclosed environment can reach market up to four weeks sooner than those grown in field production. By extending crop production a number of weeks with an earlier spring start and/or later fall harvest, different cultivars with longer days to maturity can be grown. This increases yield and variety and therefore profitability.
The enclosed environment provides other advantages including making weed and pest control significantly easier. However, high tunnels do require intensive management. Temperatures must be carefully monitored so optimal conditions for plant growth are not exceeded. (Jett.) Tradeoffs will always be made in agriculture but for now it looks as if the future looks good for hoop houses and high tunnels. Whoop-de-do!
Above: On a warm day the sides of the SOF high tunnel are rolled up to allow air circulation and prevent heat build up.
Coleman, Eliot. 1992. Four-Season Harvest. Chelsea Green Publishing Company. White River Junction, Vermont.
Jett, Lewis W. High Tunnel TemperatureManagement. State Extension Vegetables and Small Crop Specialist, West Virginia University.
Nennich, Sr., T. T., D. Wildung, and P. Johnson. 2008. Minnesota High Tunnel Production Manual for Commercial Growers.