The Roundup -

High Tunnels Can Extend the Growing Season for Specialty Crops


The high tunnel including the outside trial and water storage tank that is used to irrigate.

Horticulture Research Specialist with the Williston Research and Extension Center (WREC), Kyla Splichal has been working with the North Dakota Department of Ag Specialty Crop Block Grant Program. The experiment consists of growing specialty crops such as tomatoes, cucumbers, bell peppers, delphiniums, snapdragons, lisianthus, and dahlias in a high tunnel structure versus outside.

The project was first discussed in late 2014 by Splichal with WREC, and Esther McGinnis, Extension Horticulturist, and High Value Crop Specialist Harlene Hatterman-Valenti both with NDSU Fargo. In the spring of 2015, the group applied for an Expanding Local Specialty Crop Opportunities in North Dakota grant and was awarded the grant in October of 2015.

A high tunnel is essentially a low-tech greenhouse, or large cold frame. Unlike a greenhouse it is heated only by solar radiation, and because it has more area inside, it retains heat more effectively than a small cold frame, or low tunnel. Each end is a solid wall and two layers of high-grade thick plastic form the sides with a blower that circulates the air in between; the double layer plastic provides better insulation, and can better withstand wind, cold, and hail. The plastic sides are set on a thermostat that rolls them up as high as four feet for ventilation. The 26' x 96' structure was ordered from Rimol Supply Company out of New Hampshire, with the total cost of supplies and shipping tallying between $12,000 and $15,000.

The three main objectives for this project are to compare common varieties of traditional high tunnel crops, evaluate varieties of cut flowers, and establish an information hub for local producers-this includes the Facebook page that was created through this grant North Dakota High Tunnels.

The benefits of growing in a high tunnel are primarily an extended growing season, but also include protection from the elements and a potential for growers to get their products to market sooner. Splichal hopes that they will be harvesting as long as late October or early November, and plans to begin planting in March or April of 2017.

There are two other locations in North Dakota where high tunnels are being utilized for this project including Dakota College at Bottineau and the Dale E. Herman Research Arboretum in Absaraka.

A block of snapdragons. Photos courtesy of Kyla Splichal.

There were nine different varieties of vegetables planted in four replications within the high tunnel as well as outside next to the structure.

"I'm seeing better looking produce from the high tunnels; the plants are looking more robust and the flowers are much cleaner than the ones planted outside," commented Splichal.

Splichal plans to continue the project into the fall of 2017, and research from 2016 will be published in the WREC's Annual Report and on their website, early next year. For more information on the WREC's high tunnel, visit their Facebook page at North Dakota High Tunnels.


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