CHARLESTON — High tunnels installed in farm fields could extend the South Carolina growing season and boost production of specialty crops desired by high-end restaurants and other buyers.

Clemson University Extension agent Zachary Snipes is testing the use of these tall hoop houses made of pipe and plastic to grow vegetables at Clemson’s Coastal Research and Education Center in Charleston.

“Maybe at the end of the season when no one has tomatoes you will still have them because of these high tunnels,” Snipes told growers at the Coastal REC Field Day, which showcases various research projects ongoing at the center. “A lot of growers already have high tunnels but they’re not using them because they don’t realize how profitable they can be.”

High tunnels preserve warmth, allowing growers to produce strawberries in the fall, for example, or kale throughout the winter.

Snipes is growing horseradish; artichokes; Asian greens; tomatillos; and kallettes, a hybrid of Brussel sprouts and kale; among other crops. So far, the shield from rain and direct ultraviolet light has led to high-quality produce in the high tunnels, Snipes said. Problems with diseases like powdery mildew or insects such as cross-striped cabbageworms can be issues in high tunnels, however, so Snipes is testing various control methods to protect yields.

Clemson Extension agent Zachary Snipes speaks to farmers in Charleston about using high tunnels to grow specialty crops.

Clemson Extension agent Zachary Snipes speaks to farmers in Charleston about using high tunnels to grow specialty crops.
Image Credit: Scott Miller / Clemson University

This type of technical assistance for growers is badly needed, said Sara Clow, general manager of GrowFood Carolina, a nonprofit that serves as the connection between farmers and the retailers, chefs and institutions that buy their food. The organization is constantly working with farmers to help them navigate supply and demand of various specialty crops.

“I think high tunnels are a huge opportunity, especially here because of our climate, but there needs to be more regional specific research and training,” Clow said. “Zack is innovating, which is awesome. You have to keep innovating. Any niche specialty crop, we’re going to find a market for.”

The key will be learning how to grow these crops — and which specific crops to grow — on a commercial scale that will make economic sense, she said, because high tunnels can be expensive.

Attendees of a field day at Clemson's Coastal Research and Education Center view specialty crops grown in a high tunnel.

Attendees of a field day at Clemson’s Coastal Research and Education Center view specialty crops grown in a high tunnel.
Image Credit: Scott Miller / Clemson University

“We are looking for a consistent and diverse supply of products,” Clow said. “We’re constantly working with growers to produce a variety of crops to meet that supply and demand.”

Snipes’ high tunnels were among several educational demonstrations and research projects on display at the Coastal REC Field Day:

  • Scientists with the U.S. Department of Agriculture’s Vegetable Lab adjacent to the Coastal REC are working with Clemson scientists to develop heat-tolerant broccoli varieties that can be grown during the warm season. While not yet available to the public, these varieties have tested well in Coastal REC fields and could hit the market in the future, extending the season for South Carolina-grown broccoli.
  • A sprinkler rains water on soil sample as part of demonstration on the impact land management has on water and nutrient retention.

    A sprinkler rains water on soil samples as part of a demonstration on the impact land management has on water and nutrient retention.
    Image Credit: Scott Miller / Clemson University

    Gordon Mikell, an agronomist and soil health expert with the Natural Resources Conservation Service, used a rainfall simulator to demonstrate runoff and water infiltration in various soil types. The demonstration, in which water is sprayed onto two-inch thick soil samples before draining into buckets, demonstrates how proper land management can improve both nutrient and water retention in soil and, thus, improve farmland productivity.

  • Professor Richard Hassell is working with the USDA to develop new watermelon rootstocks with resistance to root-knot nematodes and fusarium wilt. The work is part of Hassell’s research on watermelon grafting. By grafting, growers can fuse the fruit-producing top of one plant to the root of another plant with better resistance to soil-borne disease and insects. Hassell is working to make grafting simpler and has led the development of a robotic grafting machine. He’s also working to quicken the maturity of fruits of grafted plants. Grafted watermelons typically take longer to mature, so Hassell is trying to fix that so growers have marketable fruits earlier in the season.

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