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Published July 23, 2012, 08:23 AM

Healthy eating from the ground up: 'High tunnel' method ramps up produce-growing season

Susan Bruggeman can bring vegetables to the Crookston Farmers Market earlier than most because of a new growing method, called “high tunnel,” she’s trying this year for the first time.

By: Pamela Knudson, Grand Forks Herald

Susan Bruggeman can bring vegetables to the Crookston Farmers Market earlier than most because of a new growing method, called “high tunnel,” she’s trying this year for the first time.

This past winter, when most gardeners were only dreaming about plans for plots buried in snow, she was busily planting vegetables in the greenhouse near her rural Crookston home.

In late February, she started her “crop” which included tomatoes, basil, dill, cucumbers, carrots, beets, radishes, spinach, string beans, cabbage, broccoli, sugar snap peas and eggplant.

In the spring, the plants were transferred into a high tunnel, built with metal framing covered with plastic that forms tunnel-like structures that shield the plants from natural elements — strong winds, hail and torrential rains.

“The plastic has UV protection, so the plants don’t sunburn,” said the lifelong avid gardener.

She’s “definitely happy” with the high tunnel, she said, but “there are some things I wouldn’t do again. It’s an experiment.”

The technique, not commonly used in this area, creates a protective environment that retains heat — courtesy of the sun — and extends the growing season. Raised beds keep the soil from freezing.

Optimal growing conditions

In winter months, the interior temperature of the 14-by-43-foot structure hovered between 50 and 60 degrees, she said, “a 20- to 40-degree difference from indoor to outdoor.”

Growers who use this technique report increases in production because of earlier planting dates and increases in the length of the fall harvest season, thanks to the plant-pleasing climate inside the structure.

High tunnels usually have sides that roll up, she said. Hers does not; she opens doors on each end for air circulation.

The controlled environment also protects plants from harmful insects, which reduces the need to apply low-toxicity pesticides.

Bruggeman uses no pesticides, she said.

Getting started

She first heard about high tunnels several years ago through her involvement with Crookston Farmers Market organization.

She’d been thinking about trying this method of growing vegetables for years, she said. She read books on the subject and visited a few high tunnels in the area.

At an auction last summer, she spotted some steel tubing, used in portable garages, that she thought would be perfect to create the high tunnel.

Her husband and son starting building the structure last fall and completed it this spring.

The hard work has paid off for Bruggeman who sells produce, as well as jams and other homemade food items, at the Crookston Farmers Market and a whole foods store in Fertile, Minn.

‘Like a jungle’

Come summer, “it’s like a jungle in there,” she said. She uses cable from airplane manufacturers to string up trailing plants.

In early June the produce was “going really strong,” she said, “especially the spinach, lettuce and radishes.”

She picked her first cherry tomato in late June.

“It’s been a learning experience for me,” she said. “I’ll do things differently next year.”

Her grandchildren have been eager volunteers, she said, planting alongside her.

“They’ve been coming here since they could walk. I’ve been poking vegetables in them, so they know what’s good.”

They’ve shown an interest in the high tunnel venture, too, she said. Her granddaughter, Halle, 8, whose favorite vegetable is cabbage, is impressed.

“She said to me, ‘Grandma, this is just like a garden buffet for lunch,’” Bruggeman said.

“It’s really nice to have family around to teach.”

Expansion plans

After this year’s growing season, she plans to triple the size of the high tunnel and build a dome over the entire structure.

The changes will include adding a “double cover” to provide air insulation, she said.

That covering “will lengthen the growing season by 40 days on either end,” she said.

With the modifications, she will be able to begin planting earlier in the spring and extend the growing season further into the fall, she said.

“We could have peas, broccoli and cabbage until the first of December.”

Call Knudson at (701) 780-1107; (800) 477-6572, ext. 1107; or send e-mail to