Horticulture: April 2003

Several factors determine the profitability of hoop house crops. Some of the more important include productivity (yield), variable costs (fertilizer, irrigation water, pesticides), fixed costs (hoop house structure, irrigation system, poly film) and prices obtained at the market.

Growers are always on the lookout for more productive cultivars. Consequently, as part of our hoop house research and demonstration project, we routinely perform variety trials.

Because of the increased production costs associated with growing in a hoop house, most crops are profitable only if direct-marketed. Hoop house trials at the Noble Foundation have shown that only a few crops, namely tomato, cucumber, specialty (colored) pepper and cut flowers, are profitable when grown as a single crop per growing season. Other crops are profitable only if double or triple cropped. Spreading the cost of a hoop house over two or three crops lessens the cost to grow each crop thereby increasing potential for profitability.

Like annuals, perennials such as strawberry, blueberry, raspberry, blackberry, asparagus and a myriad of flowers including lily, gladiolus and peony benefit from the growth-enhancing characteristic of hoop houses. However, the potential for profitable hoop house perennial crop production is limited because for any one planting, there is only one harvest period per growing season. For example, asparagus grown in a hoop house can be forced into production several weeks before field-grown asparagus. Fresh, locally grown asparagus available out of season is sure to command a premium price. However, considering the hoop house is generating income only 10 weeks out of 52, it is doubtful hoop house asparagus is a profitable enterprise.

Some growers are using movable hoop house structures to overcome this problem. For example, in southern Oklahoma a movable hoop house can be used to force a crop of strawberries into production during March and then moved to an adjacent location in April to protect a planting of cucumber or squash.

Because movable structures aren't anchored as securely to the ground compared to permanent hoop houses, they are more susceptible to storm damage. Most movable structures are mounted on skids or rollers and require a fairly level or uniformly sloped site to function properly.

While touring a commercial cut flower operation in southern California last year, I was introduced to a new concept in movable hoop house technology (see photos below). At this particular location, the structures are used more as rain shelters than as hoop houses. In actuality, the structures are hybrids of permanent and movable structures. The sides (ground posts) are permanent, imparting strength to the structure while the hoops are removable ensuring a high degree of flexibility. The poly film covering is secured to the structure using rope making it easy to remove and reapply. When not in use, the film can be nested to one side on top of the ground posts. Additional benefits inherent with this design include increased ventilation, ability to erect on a slope and lack of equipment height restriction.

A side view of a California hoop house. Notice the use of rope to secure the poly film to the frame.

The end view of a California hoop house.

Construction of our first removable top hoop house is scheduled for this summer. We plan on modifying the California design to make it more functional in the southern Great Plains. Specifically, modifications will focus on the design of both the end and side walls. Despite the need for modifications, I'm convinced the concept is sound.
Using removable top technology, our goal is to demonstrate profitable early and late season production of a wide range of perennial and annual crops that are not suited for production in permanent houses. Look for progress reports in coming editions of Ag News and Views.