February 2009
Featured Articles

Loophouses Can Put Vegetable Producers in the Loop!


Attention vegetable producers. What would you give to get a 50 percent boost in production? What about if that boost of 50 percent came with a marketable crop of 95 percent (rather than the usual 45-50 percent)? Interested? Let me tell you more.

When things sound too good to be true, well...they usually are; but in this case I want to give you the facts and let you decide. What we’re talking about here is not for any old crop; but rather only for high value crops like tomatoes. This crop would need to be one that would really benefit the grower if it matured a month or so earlier than usual.

The method to get this increase in yield is called a "loophouse" or a high tunnel. It’s simply an un-heated greenhouse that can help market gardeners extend their growing season and their profitability. But isn’t a greenhouse (loophouse) expensive? Dr. John Braswell at Mississippi State University said it cost approximately $0.75–1.50 per square foot. That included the plastic and the structure. You can expect to pay about 25 percent more for the end-walls, water lines, site preparation and other accessories.

Sure, there’s a cost to build a loophouse, but look what you get in return! Loophouses are used for a diversity of horticulture crops including vegetables, fruits, herbs and flowers. This passively-vented solar greenhouse (which is covered with one to two layers of greenhouse plastic) gives the optimum environment for growing high value crops (like tomatoes) with a LOT less culls.

Dr. Lewis H. Jett, Horticulture Extension Specialist at West Virginia University, said you can expect to harvest more than 15 pounds of tomatoes per plant...and many growers routinely get 20-25 pounds per plant! And, as a bonus, you can grow varieties you can’t grow in a field (due to cracks and splits from uncontrolled rainfall volumes). You can also intercrop around tomatoes for more efficient use of space (utilizing lettuce and salad crops, etc.).

Most loophouses grow crops right in the ground, which are often made into highly-composted bed areas and are moistened by two drip-line irrigation lines per row. Pine needles are often used as mulch.

At least three cropping-cycles per year are realistic for loophouses (two warm season harvest cycles and one cool season). However, intercropping extends even this scenario.

What crops are commonly grown in loophouses? Topping that list would be tomatoes, peppers, melons, strawberries and cut flowers. Tomatoes and salad greens are the top two vegetables grown in them.

To put it all in a nutshell, loophouses modify the environment to enhance plant growth...which means they elevate temperatures at crucial times of the year a few degrees per day. They also provide wind and rain protection, and often help in the control of insects, diseases and predators like rodents and birds. They improve quality, increase yields, increase market opportunities and can reduce the use of pesticides.

Want to know more? Visit www.hightunnels.org for a clearinghouse of information. Also visit Penn State’s Center for Plasticulture website at http://plasticulture.cas.psu.edu.

Jerry A. Chenault is an Urban Regional Extension Agent.