Garden Trends, Inc.
Low Tunnels - Hoop Supported Row Covers
Low tunnels are ideal for the early production of many vegetable crops. They are constructed by installing 6-foot wide sheets of either slitted or perforated plastic over wire hoops that are spaced about 4 feet apart. To prevent wind damage, the cover is pulled taut over the hoops (but not stretched), and the edges are secured with soil. Generally, the cover is left over the plants for 3-4 weeks. The slits and perforations provide daytime ventilation, eliminating the need for manual venting. Low tunnels are generally used in conjunction with black plastic mulch for weed control and enhanced soil warming.
Frost protection of 2 to 4 degrees F is afforded by the covers, but the biggest benefit is growth enhancement provided by increased daytime solar heating. However, daytime temperatures may be excessive under the cover if ambient temperatures are above 90 degrees F. Under those conditions, partial removal of the cover may be necessary, especially for tomatoes and peppers that have open blossoms.
Wire for Hoops
Number 10 gauge Smooth Galvanized Steel wire is packaged in bundles of 100. Wires are 76" long and can be inserted 6" into the soil at each end to form a support hoop that is 16" - 18" high at the center. Wires should be spaced 5' to 8' apart (see sketch below). Wire hoops are also available in 500' coils of #9 and #10 gauge wire.
Advantages of slitted/perforated row covers:
Product Description: Slitted 0.8 Mil and perforated 1 Mil row covers at are available in rolls of 6'x 1000', 500', & 250'. Number 10 smooth galvanized wire for hoops is available in bundles of 100. It is 76" long and may be used with machines designed for installing hoops and covers.
Crops that are suited for slitted/perforated row covers
The results from the use of slitted or perforated row covers on various crops will vary, but in general all crops will benefit. The primary precaution is to provide extra ventilation when there are daytime spikes in temperature. Drip irrigation and mulch are recommended as part of the growing system.
References for further information: