How Floating Row Covers Protect Garden Plants From Pests

By Blake Jackson

Floating row covers offer gardeners a practical way to protect plants from insects, reduce wind damage, and extend the growing season.

According to Susan Mahr of the University of Wisconsin-Madison, these covers are made from spun-bonded or woven plastic, polyester, or polypropylene materials. They allow air, water, and sunlight to reach plants while providing a protective barrier.

Pest Protection and Garden Benefits

Row covers can help prevent damage from several common garden pests, including cabbageworms, cabbage loopers, diamondback moths, flea beetles, onion maggots, seedcorn maggots, cucumber beetles, and thrips. They can also protect plants from aster yellows, a disease spread by aster leafhoppers.

For effective insect control, gardeners should install covers when planting to prevent pests from reaching crops.

However, crop rotation remains important because some insects overwinter in garden soil. Without rotation, emerging pests may become trapped beneath the covers and cause additional damage.

Crops that depend on insects for pollination, including cucumbers and squash, require special attention. Covers should be removed once flowering begins so pollinators can reach the plants.

As a season-extension method, row covers can increase temperatures beneath the material by approximately 2 to 8 degrees Fahrenheit, depending on their weight. This protection can reduce frost damage and help gardeners harvest certain crops one or two weeks earlier.

Choosing the Right Row Cover

Row covers are available in three general weights:

• Lightweight: Usually the most affordable option, these covers protect plants from drying winds and provide slight temperature increases. Their light construction generally eliminates the need for support structures.
• Medium-weight: These covers retain more heat, encourage faster crop development, and can improve yields. They work well with lettuce, peas, carrots, radishes, potatoes, sweet corn, cucurbits, and blueberries.
• Heavyweight: Designed for colder conditions, these covers provide approximately 4 to 8 degrees of frost protection. They can also increase daytime temperatures by 10 degrees or more. However, excessive heat above 86 degrees Fahrenheit may cause tomatoes and peppers to drop blossoms.

Installation and Maintenance Tips

Gardeners can place floating covers directly over short, flexible crops, leaving enough material for plants to grow. For pest protection, edges should be completely buried. Hoops made from PVC pipes can support covers over taller or delicate plants.

Remove covers gradually to help plants adjust to outdoor conditions, preferably finishing on a cloudy day. Store materials away from direct sunlight to prevent UV damage. Gardeners should also periodically check beneath covers for emerging weeds.

Although row covers are less common in ornamental gardens, they can provide temporary protection for valuable plants and help establish outdoor seedlings.

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