Courtesy University of MissouriWhen coupled with row coverings, high tunnels can provide added protection from low temperatures. Credit the local food movement for the increased popularity of high-tunnel production.
University of Missouri Extension horticulture specialist David Trinklein referred to the trend as creating a food production revolution, offering fresh, local produce for a longer season, according to a news release.
High tunnels may allow growers to plant earlier than if they were farming an open field, and the structures can extend harvest later in the season by offering some protection from freezes.
At night, temperatures in high tunnels average 4 degrees warmer than outside.
Sometimes called a "poor man's greenhouse," high tunnels involve a layor of plastic stretched across metal ribs. The Quonset-hut-like structure is high enough to walk under or run a small tractor through.
Crops are planted directly into the ground and irrigated with drip or microsprinkler irrigation.
They can cost as little as $3 to $5 per square foot compared to commercial greenhouses, which can cost more than $20 per square foot to construct.
High tunnels do have drawbacks. They are labor intensive and are subject to damage from heavy snow accumulation and high winds. High humidity also can be a problem.
The University of Missouri has teamed with Kansas State University and the University of Nebraska to host the www.hightunnels.org website, which provides information about high tunnel research.