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Season Extension with Low Tunnels

vegetable plants growing in a lowtunnel

In West Virginia, the first fall frost usually marks the end of the growing season. However, there are many ways to garden almost year-round. One economical method used to extend the season is low tunnel technology.

Low tunnels allow producers to achieve a four-season garden by creating a protected environment over crops. In the fall while mild temperatures still prevail, low tunnels can be used to raise the average daily temperature, and they also protect crops from low temperature injury and offer wind protection during the winter. The mini-greenhouses provide the means for producers to grow cool-season vegetables and hardy root crops well into the winter months.

A scaled down version of a high tunnel, low tunnels are constructed of wire or pipe hoops that support clear plastic or fabric row covers. Construction is relatively easy. Small low tunnels can be built using nine-gauge wire hoops approximately 18 inches in height. These types of low tunnels are best suited to short-term frost protection.

A more effective low tunnel design uses a larger hoop constructed from metal or plastic pipe. The hoop is 4 to 6 feet wide and approximately 40 inches tall at the center. A 10- to 14-foot wide row cover is placed over the hoops. Remember to use an ultraviolet-stabilized agricultural grade fabric or plastic for the row cover. Clear polyethylene plastic is not recommended in the fall, because it can overheat and increase the relative humidity. Weigh down one side of the fabric using landscaping staples or soil and bricks. Then, secure the other side with rocks or sandbags. This makes it easy to lift the cover off.

By J.J. Barrett, WVU Extension Agent – Wood County