Growing crops under tunnels may improve crop quality, extend the season and help growers earn a higher return.

For the past two years, researchers at Washington State University in Mt. Vernon have examined the feasibility of the hooped structures.

“We want to help growers on the west side get more return per acre by using high tunnels,” Tom Walters, small fruit horticulturist and high-tunnel research team member, said in a news release.

Included in the study are tomatoes, strawberries, lettuce and potatoes. The reearchers are comparing how the crops fare inside with outside production.

They also are looking to see if specific varieties may be better suited to hoop culture than others.

High tunnels resemble plastic-covered greenhouses, but are non-permanent structures.

They also have no automated heating or ventilation and are covered with a single layer of 6-mil thick plastic.

In addition, the researchers are exploring high tunnels might help control disease in organically grown crops.

“There can be few effective organic control options for some diseases on some crops,” Miles said in the release. “Growing a disease-free crop can be easier with high tunnels.”

High tunnels increase daytime temperatures and keep rain off the crops.

Crops can be started earlier in the season, and quality is improved because some disease problems are minimized because plant leaves are protected from rain.

“In western Washington, so far, we have found late blight on tomatoes and Botrytis blight on strawberries to be reduced in high tunnel settings,” said Debra Inglis, a plant pathologist and member of the research team.

For more information on high tunnels, visit