- Row covers are synthetic fabrics used to cover garden plants, usually vegetable and strawberry crops, to:
- Enhance plant growth in spring and fall by increasing the temperature and humidity.
- Extend the growing season by providing 2- 8 º F. of frost protection.
- Exclude large and small animals, especially insect pests (making it an excellent organic pest management tool).
- Row covers are an effective and flexible tool for vegetable gardeners. They require some time and attention and can significantly increase garden productivity.
Row cover basics
- Row covers are white, light-weight, non-woven fabrics made from spun-bonded polyester or polypropylene. They have a “gauze-like” appearance and resemble interfacing material used in sewing.
- Air, sunlight, and water can penetrate the material.
- Relatively inexpensive; can be easily cut to size using sharp scissors and re-used for two to three years. Row covers are available in many widths, lengths, and weights (thicknesses):
Light-weight- (0.45 oz./sq. yard) are marketed as “insect barriers,” have 90%-95% light transmittance, give 2 ºF. of frost protection, and can be left on some crops (e.g., beets, snap beans, salad greens) from seeding to harvest.
Medium weight- ( 0.5-1.0 oz./sq. yd.) have 70%-85% light transmittance and give 4-6 º F. of frost protection. For spring and fall crops and overwintering crops.
Heavy-weight- (1.5-2.2 oz./sq. yd.) allow 30-50% light transmittance and give up to 8 º F. of frost protection. For overwintering crops.
They can be purchased through mail-order seed and garden supply companies and at some local garden centers. Some brand names are Remay and Agribon. Search “floating row cover” online to identify and compare options.
How to use row covers
- Drape it over and enclose plants -- individuals, rows, groups, or entire beds -- and secure it to the ground with sod pins, boards, bricks, sandbags, rocks, or soil.
- The row cover can lie directly on the crop- hence the name “floating row cover.” The growing plants push the cover upwards if you give it enough slack.
- Alternatively, you can erect simple frames using wood, PVC pipe, #9 wire, or other available materials to support the row cover above your plants. This is recommended when using medium-weight and heavyweight row covers.
- You can buy or make plastic snap clamps and clips to secure row covers to a PVC pipe frame.
- Provide frost protection in the spring and even greater protection in fall (from soil warm-up) due to increased temperature under the cover; reduce cold damage to overwintering crops.
- More rapid plant establishment and growth in the spring and fall due to higher temperature (air and soil) and humidity under the cover.
- Row covers can reduce the time between flowering and harvest and increase harvests per unit area.
- Creates a shield around your plants keeping insect pests, mites, rabbits, deer, birds, and groundhogs from feeding on your plants. Some of the insect pests excluded- squash vine borer, squash bug, cucumber beetles, flea beetles, Colorado potato beetle, harlequin bug, Mexican bean beetle, aphids. It must be installed over plants soon after planting to be effective against pests.
Managing row covers and crops
- Cover spring transplants and newly emerged seedlings as soon as possible to hasten plant establishment and protect plants from pests, damaging winds, and intense rainfall.
- Weeds grow faster under row covers. Pull back the covers to hand-pull or cut weeds. Or lay down an organic mulch (e.g., grass clippings or last fall’s shredded leaves) before covering plants.
- Rainfall will pass through row covers but it’s best to pull the covers back if hand-watering. This also gives you a chance to cut or pull weeds and closely inspect plants for signs and symptoms of plant problems.
- Use drip irrigation or soaker hoses under row covers to irrigate plants easily and efficiently.
- For some crops like spring leafy greens and green beans, the row cover can be left in place until harvest.
- Mice love to nest in stored row cover material, ruining it for next season. Store row covers in tightly sealed rigid containers in a shed or garage or in heavy-duty plastic trash bags suspended from the ceiling. Indoor storage is the safest option.
Possible disadvantages of using row covers
- Pest insects can become trapped under row covers; pests that overwinter in the soil near host plants could emerge the following spring under the cover (e.g., root maggots, flea beetles, Colorado potato beetle).
- The temperature under the row cover can increase dramatically (5-15 ºF.) above the outside temperature leading to heat stress. For example, the flowers and fruits of bean, tomato, and pepper may drop when daytime temperatures top 90 ºF. Monitor plants growing under covers in summer for symptoms of heat stress. Plants that need protection from insect pests in summer can be covered with insect netting (more information below).
- Disease problems may be encouraged through the summer months because of increased humidity and reduced air movement.
- May abrade and injure stems and foliage during windy weather.
- Difficult to use on tall plants.
- Can rip and tear in severe storms and when in contact with rocks, stakes, wires, and other objects; UV radiation degrades the fibers.
- Row cover life is typically 1-3 years depending on the weight, use, and weather conditions.
- Made from fossil fuels; not currently recyclable.