Using Low Tunnels as an Economical Way to Extend the Growing Season
Locally produced food is growing in popularity as consumers’ interest in knowing where and under what conditions their food is grown is increasing. In the Midwest, though, most producers stop growing after the first frost and don’t have produce for up to six months a year. There is also a two to three month period in the summer when it is too hot to produce lettuce. The Millsaps use high tunnels and heated greenhouses to extend the growing season. Low tunnels are a supplement to the way they grow year-round.
Millsap Farms is a 20-acre diversified farm near Springfield, Missouri, that includes five acres of vegetables, bedding plants and vegetable starts. The Millsaps sell produce through farmers’ markets, grocery stores, a farm stand, and a community supported agriculture (CSA) program.
Curtis Millsap uses temporary low hoops with light coverings, sometimes referred to as quick hoops, as a way to extend the growing season and meet consumers’ desire for local food year-round. The hoops are made of 10-ft. galvanized electrical conduit that is bent into 6-ft. diameter half circles. The ends of the hoops are stuck in to the ground 6 to 12 in. on each side and then covered with either a floating row cover or plastic.
In 2012, the farm covered about 1,800 linear feet, or 5,400 sq. ft., of growing bed, making nine low tunnels 100 ft. long and 6 ft. wide. Crops covered included carrots, baby lettuce, beets, chard, kale, head lettuce, radishes, scallions, and spinach. Representative areas of the same crops were left uncovered for comparison.
The farm has had considerable success overwintering and extending the season three months on most of the crops. Notable exceptions are radishes, which bolted much faster under the tunnels, and lettuce, which was frostbitten by relatively mild temperatures. Crops left uncovered are almost always decimated by Dec. 1, except kale and spinach, but the beets, carrots, spinach, arugula, and kale under the covers thrived until the covers began to rip in late December and January. Keeping covers tight and well anchored are key to avoiding rips, but once one starts, it’s impossible to stop it.
Harvesting from a low tunnel is not as convenient as harvesting from a greenhouse or high tunnel, as it’s usually quite muddy and cold in the field, but the cost of a low tunnel is so much less, it’s worth it.
Next year, the Millsaps plan to expand low tunnel coverings and experiment with heavier coverings. They will continue efforts to set up effective temperature monitoring, installing devices at the beginning of the fall season.
View Curtis's presentation at the 2012 Farmers Forum through NCR-SARE's YouTube playlist. Visit www.youtube.com/NCRSAREvideo for this and other videos.
Want more information? See the related SARE grant(s) FNC10-811, Extending the Vegetable Growing Season with Low Cost Quick Hoops .
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This material is based upon work that is supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture through the Sustainable Agriculture Research and Education (SARE) program. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.