Clear Slitted Row Cover 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 2-4 degrees Fahrenheit is afforded by the covers, but the biggest benefit is growth enhancement provided by the daily increments of solar heating. Daytime temperatures might be excessive under the cover if ambient temperatures are above 90 degrees Fahrenheit. Under those conditions, partial removal of the cover might be necessary, especially for tomatoes and peppers that have open blossoms. In southern regions Insolar is recommended. This cover has a white pigment to reduce solar transmission which reduces the temperature under the cover.
Crops that are Suited for Slitted/Perforated Row Covers
Warm season crops that are subject to infection with viruses such as tomatoes, pepper, and summer squash.
Strawberries in annual hill system
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 or use insolar. Drip irrigation and mulch are recommended as part of the growing system.
Wire for Hoops: Number 10 gauge Smooth Galvanized Steel wire is packaged in bundles of 100. Wires are 76 in. long and can be inserted 6 in. into the soil at each end to form a support hoop that is 16 in. - 18 in. high at the center. Wires should be spaced 5 ft. to 8 ft. apart
Slitted Clear .8 mil (warm) w/ 2 rows of slits, 6 ft. x 1000 ft., 6 ft. x 500 ft., and 6 ft. x 250 ft rolls
Punched Clear Pole .8 mil 3/8 in. holes; 4 in. spaces, 6 ft. x 1000 ft., 6 ft. x 500 ft., and 6 ft. x 250 ft. rolls
Clear Poly - no holes or slits, 6 ft. x 5600 ft., and 6 ft. x 1000 ft. rolls
Wire for Hoops-Number 10 smooth galvanized wire; 76 in. Long (100/bundle)
Advantages of slitted/perforated row covers:
Outdoor crops may be planted about 10 days earlier than normal
Highest heat retention with clear perforated covers and slitted covers
Prevention of excessive heat with Insolar
Earlier maturity and higher yields
No manual ventilation is necessary
Excellent for tomatoes, pepper, cucumbers, melons, and many other crops
Space hoops about 4 ft. apart to prevent sagging of the covers.
Apply covers on a calm day.
Apply the cover taunt and secure the edges with soil.
Machines are available for hoop and cover installation.
To prevent weed growth under the cover, install the cover right along the edges of the black plastic mulch.