High tunnels can extend season and improve yields, quality

07/11/2013 03:37:00 PM
Tom Burfield

The structures typically can be depreciated over 10 years, but they have at least a 20-year lifespan, he says.

Although high tunnels can be found statewide, most of the large concentrations are in Central and South Florida, Hochmuth says.

They present a unique advantage in Florida because many consumers in urban centers now want locally grown, high-quality specialty crops.

Even small-scale growers often can meet that demand because they can achieve greater yields on less acreage, he says.

Grower experience

William “Skeeter” Bethea, a crop specialist for Enza Zaden specializing in tomatoes and peppers for the East Coast, logged 25 years as a conventional grower before venturing into developing high tunnels and the seed varieties best suited for them.

Bethea, who’s based in Myakka City, is conducting a commercial demonstration trial in a series of connected high tunnels with passive ventilation designed to “get the heat out.”

Inside the tunnels are several tomato varieties along with peppers and cucumbers.

“You can’t build any business on inconsistent product flow,” he says. And an overheated tunnel can disrupt that flow.

His tunnel design, which has been picked up by Tunnel Tech of Tilsonburg of Ontario, Canada, features end-cap vents and roll-up doors to aid airflow.

Yields from 1 acre of a high tunnel can equal those from 7 acres of open-field production, Bethea says.


The biggest challenges in setting up a high tunnel are the upfront invest ment—the cost of the structure—and making sure the structure can withstand the environment, Hochmuth says.

In Florida, that often means high winds.

High tunnels create a very different environment than what growers are used to, he says, so you’re going to have to change some growing practices.

For example, pest pressure is different.

Instead of the common pests that you might find in the field, the dry greenhouse environment may result in more pests, such as spider mites and powdery mildew.

You also may have to change your variety or cultivar choices.

“[Growers] have to be in a position to make a wise choice in terms of what cultivar they’re going to grow,” Hochmuth says. “That’s where we are having a hard time keeping up with the demand for information.”

If you have a large operation and the equipment to do soil fumigation, you can continue to use it or switch to a soilless environment, Hochmuth says.

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