Many vegetables grow well in high tunnels

COLUMBIA, Mo. While tomatoes are the most popular choice for high tunnel production, many other vegetables, fruits and flowers flourish in the controlled environment of high tunnels, said University of Missouri Extension regional horticulture specialist James Quinn.

Researchers at MU’s Bradford Research and Extension Center have been growing plants in high tunnels for more than a decade.

During a 2005 variety trial, cucumber plants were planted in soil recently occupied by tomato plants. The cucumbers grew on a trellis and yield was doubled over traditional planting, up to 10 pounds per plant, Quinn said.

He said cucumbers do well as spring and fall crops. Parthenocarpic cucumbers are the best choice for growing in high tunnels because they don’t need a pollinator to set fruit. Powdery mildew, thrips and spider mites are common problems cucumber growers may face.

In a demonstration trial in 2009 at Bradford, zucchinis were direct-seeded using parthenocarpic and non-parthenocarpic varieties. Yields averaged about 5 pounds of zucchini per plant, though Quinn noted that yellow varieties of zucchini did not fare well, and powdery mildew was a problem.

In a 2003 trial, green bell peppers were seeded on April 29, transplanted June 5 and yielded 6 pounds of peppers per plant.

Direct-seeded lettuce, spinach and other garden greens offer a high profit potential for growers. In a 2005 Kansas State University study, fall spinach yielded 3-10 pounds per 10 square feet and was harvested two to four times. The spinach was planted Oct. 6 to Nov. 17 and harvested until March 26, 2006.

Cole crops such as broccoli, cauliflower, cabbage and Napa cabbage do well in high tunnels, Quinn said.

Strawberry crowns can be planted in September, but Quinn said it is sometimes vexing to establish crowns. Another challenge is inducing and maintaining winter dormancy by having the tunnel open in December and January. A pollinator is needed for the best results, he said. A marginal 25-percent yield increase over growing traditionally has curbed grower enthusiasm. Gray mold and spider mites also can be a problem.

Raspberry yields were up to three times greater in high tunnels, and fruit quality and size were greatly improved, Quinn said.

Melons can be grown on trellises in high tunnels, but they have to be netted to keep from dropping from the vine. “They are a lot of trouble for what you get,” he said.

Other planting options include herbs, cut flowers, eggplant and green beans.

For more information on high tunnels, go to www.extension.missouri.edu and enter “high tunnels” in the search box.

Information about high tunnel research is also available at www.hightunnels.org, a joint effort of MU Extension, Kansas State Research and Extension, and University of Nebraska Cooperative Extension.