High tunnels increase growing season, exotic crops and conservation

April 09, 2010

University Park, Pa. -- Some say there's nothing new under the sun, but researchers in Penn State's College of Agricultural Sciences are finding new ways to squeeze more out of it every year by extending Pennsylvania's growing season. They're also squeezing more out of this geographic growing zone by producing exotic fruits and vegetables normally found in more temperate southern climes.

Scientists are doing this by perfecting the use of high tunnels, or "hoop houses," which have proven themselves as effective options to increase the availability of locally grown produce in a conservation-friendly way, according to Mike Orzolek, professor of vegetable crops and director of the Penn State Center for Plasticulture.

Unlike greenhouses, which are heavy, expensive to build and difficult to move, high tunnels are plastic-covered, lightweight structures with skeletal ribs of metal or plastic. They are easy to build, maintain and relocate. In addition to extending the growing season -- and perhaps a grower's bottom line -- high tunnels also may help reduce pesticide use, keep vital nutrients in the soil, increase yields and provide other benefits to growers.

High tunnels also can supply the market with exceptionally fresh produce and very unusual items, noted Orzolek. "Local grown, local fresh is really hot now," he said. "In July and August, crops usually are harvested within 24 hours of being brought to market. It's extremely fresh."

Orzolek explained that 100 percent of the sold produce grown in Penn State's high tunnels ends up at the Cellar Market, an old potato storage cellar converted to a sales stand on the University Park campus between Tyson Building and Eisenhower Auditorium. The market is operated from May through December by Department of Horticulture students and staff.

Some of the first sales items of the season are not foodstuffs, but young plants. Seedlings are propagated in the high tunnels and then brought in for homeowners to transplant, according to Orzolek.

Around June, after the planting season, the tunnels start to produce blueberries, then early tomatoes and broccoli. As the season progresses, peppers, snap beans, flowers, strawberries, small fruits, raspberries and herbs become available, he said. By late August, the items become less specific, Orzolek said, but fresh tomatoes, peppers, Asian vegetables and ethnic greens are available six to eight months per year.

"We try to get unusual things there -- bitter melon, hot peppers, simply sweet onions, cabbage, kales, garlic and about 30 different vegetables and small fruit," he said. "We like to try new things for consumers to see, and see consumer acceptance or rejection. We get a pretty good read of what individuals think, and the students who work there get an education on what consumers are buying and what remarks people make."

Novelty produce also enjoys a certain place in the sun at the Cellar Market, according to Orzolek. "It's a great place to test consumer interest in a product, like white, purple, yellow and green cauliflower, or pink, purple or yellow tomatoes." He said consumers don't seem too excited about the unusual colors -- most still prefer white cauliflower and 95 percent still pick out red tomatoes.

He said this provides valuable information for producers. "Even if they can sell me a color I'm not used to, I probably won't buy it. We can grow yellow-skinned watermelons with red flesh, but they probably wouldn't buy it," he said.

Potato buyers follow the same trend. Although spuds can be grown in blue, flesh, red or yellow hues, they account for less than 10 percent of total sales. "Just like people's parents or grandparents were meat-and-potato people, the potato had to be white with brown skin," he said. "They simply can't do a blue potato."

Researchers also are studying optimum high-tunnel cropping systems and rotations. "The newest thing we're looking at is movable tunnels that ride on rails," Orzolek said. "If you only have one set of high tunnels, but can move them three times, it's like having three sets of high tunnels for the price of one."

He said that long rows -- 1,000- or 2,000-foot runs -- can be created to stage crops throughout an extended growing season. Tunnels can be placed over perennials such as cherries, apricots and peaches to get them past the first frost, and then moved down-range, when the heat would be too great for the trees but excellent for annual crops such as blueberry, raspberry, lettuce, tomato, pepper and summer squash, which do extremely well in tunnels. The third move can accommodate leafy greens well into December or even January.

Orzolek said the cost for tunnels on rails is about double that for stationary tunnels, but the potential for having three crops -- and thus three harvests -- could pay back the total costs in a year-and-a-half.

Pennsylvania is one of 38 states participating in a three-year study to verify whether high tunnels are effective in reducing nutrients, sediment and pesticides in watersheds, conserving ground and surface water resources and reducing soil erosion. Federal funds are available for growers to convert to high-tunnel production if they are established producers moving toward high tunnels or if they are beginning producers who intend to grow 100 percent organic crops.

USDA's Natural Resources Conservation Service (NRCS) will provide financial assistance for projects through the Environmental Quality Incentives Program (EQIP), the EQIP Organic Initiative and the Agricultural Management Assistance (AMA) program. To sign up or learn more about EQIP assistance for high tunnel projects, contact a local NRCS office.

According to Ed Sanders, EQIP Manager for Pennsylvania, the program will fund $2 per square foot up to 2,178 square feet for qualified participants.

"If you're a young grower, and you want a high tunnel, this funding program is ideal, because you only have to pay about 25 percent of the cost," Orzolek said.

  • Red bok choi grows among other Asian vegetables in high tunnels at Penn State's Horticulture Farm.

    IMAGE: Greg Grieco
Last Updated November 18, 2010