Extending the Vegetable Growing Season

Home Grown  by Keith Reed
While our latest cold snap might rightfully give cause for doubt, spring gardening season will be here before we know it. If you’re anxious to get started as soon as possible in order to get the maximum production out of the growing season, you may want to consider using some simple season extension structures. Terms for these can vary but they are commonly referred to as hoop houses, low tunnels or high tunnels. In Oklahoma, these structures can extend the growing season approximately one month, both in the spring and fall.

On first glance, these structures resemble plastic covered greenhouses. However, there is a fundamental difference. Greenhouses are permanent (or at least semi-permanent) structures with supplemental heating and cooling capabilities. Season extension structures, we will refer to them as hoop houses for the balance of this discussion, do not have these features.

Hoop houses rely strictly on the power of the sun for heating. Once the soil is warmed under a hoop house, it creates a significant heat sink that allows plants to survive most early spring/late fall cool temps. In cases of unusually cold weather, an additional layer of protection in the form of frost blankets can be draped over the plants to provide another 5-10 degrees of cold protection.

There are a couple of important points to note when considering gardening with a hoop house. You must be prepared to be available on short notice to open and close the structure up as the temperature fluctuates. While cold weather is self-explanatory, excess heat can be just as much of a problem as temperatures inside a closed up hoop house can easily exceed 100 degrees on a warm spring day. Also, you must also be prepared for extreme weather events that the hoop house simply can’t protect from.

While most gardeners remove the plastic when the weather warms, some continue to grow under plastic year-around. Some of our state’s best suppliers of Farmers Market tomatoes are doing this and having great success. The cover helps manage moisture, disease and damage from wind. This isn’t necessarily something a home gardener will want to try the first year of hoop house growing, but it gives you some idea of the potential advantage this method holds.

See OSU Fact Sheet #HLA 6720 High Tunnels (
PDF/Mobile) for some helpful information. For real-world examples of hoop houses in operation, go to Oklahoma Gardening’s channel on YouTube.com and type hoop houses in the search box. You’ll find several show segments featuring the topic.

For more information on this or any other horticultural topic, you can contact Keith Reed, the Horticulturist in the Payne County Extension office. Keith can be reached via email at
keith.reed@okstate.edu, phone at 405-747-8320, or in person at the Payne County Extension office, located at 315 W. 6th in Stillwater.

Oklahoma State University, in compliance with Title VI and VII of the Civil Rights Act of 1964, Executive Order 11246 as amended, Title IX of the Education Amendments of 1972, Americans with Disabilities Act of 1990, and other federal laws and regulations, does not discriminate on the basis of race, color, national origin, gender, age, religion, disability, or status as a veteran in any of its policies

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