Experience with high tunnel production: Annual crops that have done well in southwest Michigan

Tomatoes are usually the crop of greatest interest to many tunnel producers, but other crops perform well and should be considered, including many flowers, leafy greens, herbs, cucumbers, pole beans and lesser known crops like okra.

Even though the main crop in our tunnel trials at the Southwest Michigan Research and Extension Center (SWMREC) has been tomatoes, we have planted other crops to observe how they perform. Vegetable crops performing consistently well include beit alpha cucumbers, pole beans (Photo 1) and okra.

Pole beans Cucumbers
Photo 1. High tunnel-grown pole beans (left) and cucumbers (right). Photo credit: Ron Goldy, MSUE

Cucumbers need extensive training and support just as in greenhouse production. Pole beans make a good follow-up, late season crop after the main crop is harvested. They have no trouble finding and climbing support strings, but most pods need harvesting from a ladder.

Okra does well because of the increased temperatures and is easier to harvest since the tunnel conditions extend internode lengths. Eggplant does well but gets tall, bushy and hard to manage; a reduced fertility program may be needed. Peppers need additional support since they get tall and easily fall over under the crop load. Leafy vegetables like lettuce and spinach, and herbs such as basil and parsley, have done well. Part of the reason these do well is the plastic covering reduces light by at least 25 percent, creating a partial shade environment contributing to larger leaves.

Certain flower species have done well – others have done poorly. For those that do well, flower color appears more intense and size is larger. Stem lengths on cut flowers are also longer, again due to the partial shade conditions.

Flowers that have flourished include zinnias (Photo 2), some ornamental grasses (Photo 2), snap dragons, statice, sunflowers (not the real big ones), tithonia, gomphrena (Photo 3) and eucalyptus (Photo 3). Those that do poorly generally do not like high temperatures, including dahlia, cosmos, bachelor buttons, delphinium and gladiolus.

Zinnia Ornamental grasses
Photo 2. High tunnel-grown zinnia (left) and ornamental grass (right). Photo credit: Ron Goldy, MSUE

Gomphrena Eucalyptus
Photo 3. High tunnel-grown gomphrena (left) and eucalyptus (right). Photo credit: Ron Goldy, MSUE

Without support, taller flowers tend to fall over and develop crooked stems. A good support system is to simply place 2-foot stakes 1 foot in the ground and stretch chicken wire over the stakes (Photo 4). Flower stems grow through the fence openings and can easily be harvested.

Chicken wire fencing
Photo 4. Snap dragons supported with a 2-foot chicken
wire fence stretched between cedar stakes. Note the stakes
at top of picture (red circles). Photo credit: Ron Goldy, MSUE

For high tunnel research reports generated by Michigan State University Extension at SWMREC, go to the SWMREC Annual Reports website and look at the Annual Reports starting in 2005.

For more information on commercial vegetable production, contact Ron Goldy at 269-944-1477 ext. 207.

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