A high tunnel is a plastic-over-frame, generally unheated version of a greenhouse. It is relatively inexpensive--1/10 the cost of a greenhouse. Crops are planted directly in the ground. They are watered by drip tape that is laid on the ground or buried about an inch under the soil. There are no fans. Crops are vented by rolling up the plastic sides of the tunnel.
High tunnels are especially important to growers who want to get a jump on the season, and they also allow growers to extend the season into the fall. Consumers pay a premium for early produce like tomatoes and, if farmers can market food for a few extra weeks each season, it means a lot to the bottom line.
Loralee said she plants several varieties of tomatoes and 35 varieties of (primarily) hot peppers in the Ter-Lee high tunnels. The varieties are not the normal types grown in Minnesota. High tunnels get really warm, so Loralee grows varieties native to hotter climates. She and Terry have to be sure the tunnels are vented before it gets too warm inside on any given day.
My online searches showed that the tunnels are a little more involved than I originally had hoped, but definitely do-able for the home gardener. There are high tunnels at the North Central Research and Outreach Center in Grand Rapids. Dave Wildung at the Center was another pioneer, along with Terry Nennich, of the high tunnel method. There is also a MN High Tunnel Production Manual available online from the University of MN Extension Service.
The folks from Ter-Lee Gardens come to the Bemidji farmers’ market at the Pamida parking lot three days a week—Sundays 11-4, Tuesdays 9-5, and Thursdays noon-6. They produce asparagus, strawberries, and 30-40 types of vegetables from early July through November 1.