How to Control Garden Pests

Here are some natural and nontoxic ways to protect your flower and vegetable gardens from pests and diseases.

Nontoxic Pest Control

No garden is free of pests and disease. Fungal infections, caterpillars, beetles, dogs, deer -- the list of potential problems is seemingly endless. Fortunately, you can fight back against these predators without risking your health or spending a fortune. In many cases, simply by changing the way you garden, you can head off problems before they arise.
The tips below can be used together to form a protective barrier against the most common crises that arise in both vegetable and flower gardens. Many problems can be attacked on several fronts, so if one solution fails in your garden, try another. Above all, stay vigilant; it is much easier to protect your garden if you act before, or at, the earliest signs of trouble.

Mechanical Barriers

Many predators can be controlled by blocking their access to your garden. The most common system is a simple fence, sized to repel the expected invader.
Fences. Dogs and rabbits may be deterred by a low fence securely attached at ground level or, even better, buried several inches into the ground. Larger pests -- notably deer -- may require much taller fencing which, unfortunately, can be prohibitively expensive or unsightly. Many plants are susceptible to attack only when young and tender. Consider surrounding these plants with individual collars of fencing.
Row covers. These lightweight sheets of fabric cover plants without smothering them, and allow light to pass through. Commonly used in commercial nurseries to protect tender plants from light frosts, row covers can also provide a measure of protection to vegetable crops from insects, caterpillars, birds, and lazy rabbits and squirrels. Row covers are most useful when transplants are young; remove them as the plants' stems harden.
Cloches. Sometimes you need to protect just one plant or a row of plants. A cloche is a temporary cover sized and shaped to fit a particular situation. For single plants, you can cut the bottom off a gallon plastic milk jug and set it over the plant. Small plants can be covered with paper cones secured to the ground with landscape pins. And row crops can be protected by tunnels created with wire hoops and row-cover fabric. The primary danger with cloches is heat buildup on sunny days. Remove or vent the cloches before they can overheat and fry your plants.
Cutworm collars. Cutworms are night-crawling pests that chew through plant stems at ground level; they are particularly fond of young transplants of broccoli, cauliflower, and their relatives. Foil cutworms by forming 2- to 3-inch-diameter collars out of large index cards. Slip a collar over each transplant and push the collar an inch or so into the soil.
Netting. Sold as bird netting, this lightweight mesh is perfect for protecting berries and tree fruit from winged marauders.
Chemical barriers. Some gardeners use animal scent products, like fox urine or dried blood, to deter pesky animals. The jury is still out on the effectiveness of these products, but they might be worth a try. Just remember that you may have reapply these products frequently, especially in rainy climates.

Pick Disease-Resistant Plants

Various diseases and fungus infections can destroy or disfigure a wide range of garden plants. Leaves with a powdery appearance or strange coloration are common signs of infection. The key to beating diseases is prevention; many problems are difficult or impossible to control once they get a foothold.
Pick disease-resistant varieties. This is the most critical step a gardener can take to control all sorts of diseases, including fungal infections. Scan catalogs or Web sites for plant varieties that are described as disease resistant. Talk to reliable nursery and garden center staff.
Give plants space. Fungal infections need moisture to grow and spread. Tightly spaced plants don't dry as quickly after a rain, giving the fungus more opportunity to develop and spread. Don't space plants closer than recommended, and in humid areas, give them a little more room.
Keep leaves dry. To keep leaves as dry as possible, avoid overhead watering; instead, water around the base of plants when possible. If you are growing vine crops, like some tomatoes and cucumbers, support the plants on trellises so leaves and fruit aren't in contact with damp soil.
Get rid of diseased plants. Check plants often for signs of problems. Diseased or dead plant material should be removed from the garden immediately and thrown in the trash. To prevent reinfection, don't add sick plants to your compost pile.
Rotate crops. Some disease-causing organisms will overwinter and multiply in the soil beneath a susceptible plant. Vegetable gardens are particularly at risk for this problem. To keep such diseases in check, change where you grow a particular crop each year. For instance, if you grew tomatoes in the northeast corner this year, plant them in the northwest corner next year. Rotation of crops also helps promote better soil fertility.
Test (and fix) your soil. Many (though not all) plants grown in poor soil or soil that is too acidic or alkaline will quickly develop problems. Your local county extensive service can inexpensively test your garden soil and recommend changes to fix deficiencies. You should also plan to add organic matter to your soil regularly to improve its structure and water-holding ability.

Insect Control

Not all crawling and flying critters are bad for your garden. Without bees to pollinate them, broccoli, squash, apples, and many other food crops would fail. And many insects perform a service by destroying other, harmful, insect pests. Lady beetles, for instance, can help control aphids. Spraying powerful insecticides destroys good bugs as well as bad, and should be avoided if possible, particularly when bees are present. Instead, consider using natural and nontoxic insect controls.
Pick 'em if you got 'em. Larger insect pests and harmful caterpillars can be hand-picked if the infestation is limited. Once you get over the "yuck factor," this approach is easy and effective.
Waste management. Remove and destroy infested plants; don't add them to your compost pile. Also, remove dead leaves, fallen fruit, and other debris that can provide refuge for pests.
Use nontoxic sprays or traps. Insecticidal soap sprays are fairly effective on many pests, and won't harm plants, people, animals, or beneficial insects that come along later. You can find these sprays at most garden centers. Some manufacturers are also producing insect traps with scents that lure harmful insects to sticky pads, similar to old-fashioned flypaper. To lure slugs to their death, some gardeners sink beer-filled saucers in the ground around their prized plants.

Keeping Weeds at Bay

Like death and taxes, weeds are inevitable. Although you can't rid your garden of them completely, you can keep them to a manageable level.
Use mulch. Mulch offers plenty of benefits including keeping weeds down, cooling the soil, and preventing evaporation of moisture. Organic mulches also feed the soil as they break down.
Control weeds early. Young weeds are easier to remove or destroy; in the long run, frequent light weeding is less taxing than waiting until the weeds take over. Getting them young also ensures that the weeds won't develop seeds that will germinate in the future.
Apply a safe pre-emergent control. A corn-based chemical found in some weed-control products (Preen is the most widely known brand) prevents annual weeds from developing. Because these products don't affect established plants, these products can be sprinkled in the flower gardens in the spring, before seeds have sprouted, to control many common weeds. Bear in mind, however, that pre-emergent controls don't work on perennial weeds and annual weeds that are up and growing.