Better Pest Management
Companion planting, interplanting, and healthy soil tricks that keep pests away from your vegetables.
We like the way Edward C. Smith thinks about insect pests. As he states in his fine book The Vegetable Gardener’s Bible, he treats pests (and that includes disease) as predators on the hunt. “Just as lions select the weakest wildebeest, aphids are drawn to the weakest plants,” he writes. “Anything you can do to improve growing conditions for a plant makes the plant less likely to be attacked by pests and disease. Good pest management means understanding that pests and diseases are not problems in themselves, but symptoms of the problem.”
Smith doesn’t use the term Integrated Pest Management. But of course, that’s what he’s doing: not using chemical pesticides to take care of his problems (which often causes even more garden problems in addition to exposing you and your family to dangerous compounds) but instead using a variety of non-chemical techniques to discourage and control insects that might want to invade his plants.
Of course, the groundwork (pun intended) for producing healthy, pest-discouraging plants is done with your soil. Soil should be conducive to best growth. The general principles of building healthy soil — like adding lots of rich, organic natural matter in the form of compost — apply. But fine tuning is also required. Different plants favor different conditions and a one-size-fits-all approach may not be the best solution to all the various vegetables you intend to plant.
Start with soil pH. Without the proper soil pH plants won’t have access to all the nutrients they need. Some plants, like beans, cabbage, squash, and tomatoes will tolerate higher pH levels. Some like asparagus and Brussels sprouts will not. Testing soil pH each year is important (see Soil Test Kits). Adjusting the pH in each row or plot for particular vegetables can be equally important. Of course, this is more easily accomplished in large gardens than in small. But if you’re planting a particular crop in a raised bed or square-foot space, it’s easy to adjust pH as long as you’ve planned ahead. See more on adjusting pH here.
Fertilizing can also make a difference. As Smith points out, too much nitrogen in your soil can make your plants attractive to aphids and whiteflies. Wireworms, the potato — loving larvae of click beetles, can be discouraged if your soil in rich in phosphorous and potassium.
There are other ways of confusing and discouraging insects that come of good garden planning. Companion planting, of course is one. While there’s some controversy about the technique’s effectiveness, there’s little doubt among gardeners that some tried-and-true companion planting techniques, such as planting celery to deter white cabbage moths, have benefits. These techniques work best when your plants are healthy and not attracting predator pests through weakness.
Another great way to confuse pests is through interplanting. Who says every vegetable must be planted, like soldiers ready to march, its own row? Why have all the cabbage in one place where the moths can easily find them? Mixing your plants up in the garden will not only make your plants less visible to insects, it will also help keep disease you might accidentally introduce into you plant through transplants from spreading easily. Interplanting takes some planning but can be effective, especially when coupled with the principles of companion planting.
Of course there’s a lot more you can do — like employing row covers, attracting and utilizing beneficial insects, and keeping a clean, weed-free garden — as part of a successful integrated pest management program. But keeping plants healthy is job number one.
If all this seems too much trouble — and we know a lot of gardeners who go to extreme lengths to combat insects and avoid pesticides — just do what needs to be done to make sure your plants are at their healthy best: make sure your plants have sufficient and regular water, keep your plants safe from the stresses of temperature and water extremes by using mulch around your plants, and keep a layer of compost around on the ground around your plants at all times. Plan to do at least this much and you’ll have great results.