Row covers can protect plants in the garden

Garden catalogs are arriving, making gardeners think about last year’s garden and what we can improve on this year. If you had issues with insects and diseases last year, or wish to extend the garden season to earlier in spring and later in fall, you might consider row covers.

Row covers are lightweight white gauzy fabrics that allow air, water and sunlight to penetrate while keeping out insects and pests that cause crop damage and carry diseases.

Row covers come in light, medium and heavy weights, all allowing different levels of light through, and providing more frost protection the heavier the covers are. You can drape the lightweight fabric directly over the plants and secure the fabric to the soil with bricks, rocks, soil, etc. Be sure to allow enough slack in the fabric for the plants to push the cover upwards as they grow. You could also make a simple frame using wire, PVC piping, cement blocks, etc., to support the row cover above your plants, es-* pecially if using heavier weight covers.

The covers will provide some frost protection in spring and fall and also promote higher temperatures and humidity under the cover, which helps to extend the growing season. The covers create a barrier around the plants to keep insects and wildlife from feeding on your plantings.

In order to be effective against pests, the cover must be placed immediately after planting. Some insect pests that could be excluded are squash vine borers, Colorado potato beetles, aphids, allium leaf miner, etc. One possible disadvantage to using row covers is that insects that over winter in the soil can emerge in spring inside the row cover. Allium leaf miners, for instance, over winter in the soil and can easily be enclosed in the row cover at planting time.

Insects covered with a row cover are protected from their own predators, allowing them unimpeded access to your garden plants. This is another reason why crop rotation is important; for instance, if you plant onions in an area where you did not grow them last year, you have less chance of the new planting being near over wintering allium leafminer pupae. Also, remember that the cover is protecting weeds and allowing them to grow faster, too, so you’ll need to pull back the covers regularly to weed, and to scout plants for insect pests and damage.

You’ll also want to monitor your plants for heat damage as the temperature under the cover can be 5-15 degrees higher than the outside temperature. Be sure to remove it when temperatures are forecasted to reach 85 degrees. Row covers can be reused for several years if stored properly.

Mice tend to ruin the fabric during winter by using it for nesting material so you might consider using a mouseproof container for storage. If you would like further information on this or other gardening topics, contact the Penn State Extension Master Gardeners of Berks County at berksmg@psu. edu or phone the office at 610378-1327.