Time Your Plantings to Avoid Pests

Out-smart common garden pests by strategically timing your planting.


European Corn Borer

Another sweet corn menace that can be outwitted by planting time! This caterpillar is a pest in northern and central United States and southern Canada. Bent tassels or broken, chewed leaves and ears with holes in them are the signs of European corn borer damage.

To combat this corn pest, you must avoid very early and very late corn plantings. For most, that means planting corn about 2 weeks after the last frost date (or as close as possible to the midpoint of your corn-planting season). If your corn usually suffers from both of these pests, choose the timing that will beat your most troublesome pest.

Flea Beetles

These jumpy little black beetles chew small, rounded holes in the leaves of many vegetables (such as brassicas, eggplant, potatoes, and tomatoes). They sometimes kill seedlings. If you've had flea beetle problems in previous years, avoid them by delaying the planting of susceptible crops by a week or two beyond normal planting times for your region.

Because flea beetles overwinter as adults, full-size adult beetles appear in your garden very early in the season. If food isn't there when the adults emerge, they won't lay their eggs in the garden, which means fewer problems later in the season. When you do plant, use transplants rather than direct-seeding your crops whenever possible—transplants can withstand flea beetle damage much better than young sprouts.

Mix Up Flea Beetles: Timing planting right helps prevent flea beetle problems, and so can interplanting, says Sally Cunningham, author of Great Garden Companions. "One year I planted eggplants all alone in one area, and in another place, I interspersed eggplants with marigolds and basil," Sally says. "Guess what? The solo eggplants were full of holes, but the other ones were camouflaged enough that they squeaked through the season undiscovered! Flea beetles are easily confused."

Pepper Weevil

Found across the south from California to Florida, these weevils puncture immature peppers with their sharp snouts and lay eggs in the peppers. The eggs hatch and the larvae feed on the peppers, causing them to turn yellow, get misshapen, and/or drop from the plant.

But you won't witness such horrors in your garden if you start your peppers indoors and plant them outside as early as possible (about 2 weeks after the last frost), before the weevil population builds up. At the end of the season, get your peppers out of the garden as fast as possible, too—allowing the plants to linger will invite future weevil problems.

Root Knot Nematodes

These tiny, eel-like creatures feed on the roots of almost all veggies and are especially problematic in the warm, sandy soils of southern and coastal regions. Affected plants look weak and sickly. Their roots are covered with galls (knobby, abnormal growths).

Early spring planting (at least 4 weeks before the last frost) is the key to getting a good harvest of crops like lettuce, broccoli, and cauliflower, because nematodes don't become active until soil temperatures are fairly warm. Start your broccoli and cauliflower indoors about 12 weeks before the last frost and plant them outdoors when they are 7 to 8 weeks old. Lettuce and other greens should be started 8 weeks before the last frost and planted outside when the seedlings are 4 weeks old.

In fall, reverse this timing: Delay lettuce, spinach, and other cool-season plantings until the soil temperature drops below 64ºF. Choose nematode-resistant varieties when you can.

Sweet Potato Whitefly

These tiny, sap-sucking insects attack vegetables just about everywhere in North America. When infested plants are disturbed, clouds of adult whiteflies fly into the air. The greatest damage to plants is done by the viruses they transmit.

Allowing 2 weeks between crops is an effective way to control whiteflies. After you harvest one crop, clean up and allow a 2-week fallow period before planting the next. Sweet potato whiteflies will have nothing to feed on during those 2 weeks and will either die off or move on.

In the fall, a simple delay in planting will help. In the South, wait about 2 weeks after the late summer cotton harvest to avoid the masses of whiteflies that were feeding on the cotton.

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