COMPANION PLANTING
The practice of companion planting has been going on for centuries. Now that everything green is chic again, it’s fashionable once more. It’s easy, can produce excellent results and often reduces or eliminates the need for pesticides.
Companion planting simply means pairing or grouping different kinds of plants that perform beneficial functions for each other. Native Americans did it with the famous “three sisters”–corn, beans and squash. Beans fix beneficial nitrogen in the soil, which helps the corn, which in turn provides support and protection for bean and squash vines. All three species prosper and Native Americans and subsequent generations of wise farmers and gardeners have benefited from higher yields as the result.
The simplest kind of companion planting involves a practice that we plant collectors use instinctively–installing a wide variety of plants in our gardens. This horticultural smorgasbord confuses pests, attracts a variety of pollinators and contributes to biodiversity. Monocultures, or large groupings of a single plant variety, draw plant predators like magnets. Whether the monoculture is a perfect lawn, a breathtaking rose garden or an acre of petunias, you might as well put up a sign that says “All You Can Eat Buffet” for the aphids or grubs or other insect varmints. Unless you enjoy activities like handpicking Japanese beetles full time, you are going to have to use heavy doses of pesticides to control the predators that will besiege your plants. Of course there are organic pesticides, but I think it’s much easier, safer and more practical to put in some companion plants.
Members of the mint family have a reputation for repelling creatures ranging from aphids to mice. I find that underplanting my roses with catmint or Nepeta keeps down the aphid population and may also repel earwigs. Basil helps tomatoes by repelling insects. The leafy mint relative may also help boost tomato flavor and vigor when planted close by. Since the two plants are natural culinary partners, they make great companions–either in the garden or in pots.
Many people won’t plant mints because mints are notoriously invasive. However, pot culture allows you to have your mint without worrying about it surging over your other plantings like a tidal wave. It’s very easy to place an array of potted mints throughout the garden and you can even make the pots disappear by sinking them into the soil. As companion plants mints are also highly desirable because they attract all kinds of bees, butterflies and other essential pollinating insects. If you are worried about attracting bees to sitting areas or the places where your children play, planting mints elsewhere in the yard or garden will draw them away.
For generations farmers have surrounded their kitchen vegetable gardens with borders of marigolds. The plants’ pungent aroma repels pests and the roots secrete a chemical that deters harmful nematodes. Even if you don’t particularly like the aroma of marigolds, they are worth installing in vegetable or flower gardens because of their pest-controlling ways.
Another form of companion planting provides an alternate host for plant predators. Install eggplant next to potatoes, for example, and the potato beetles may prefer the eggplant. You may lose a few eggplants, but you will preserve the potatoes.
Refugia are plantings that provide habitats for beneficial species. A classic example of refugia are traditional hedgerows, the areas between farmers’ fields that are deliberately left uncultivated. Refugia usually house birds, small animals and a variety of insects, many of which are beneficial to crops. Most of us don’t have enough space for traditional refugia, but we can plant a variety of shrubs and small trees, especially around the perimeters of our properties.
The important thing about companion planting, or any “green” practice, is that you approach it as a simple, practical solution, not an onerous burden. With our heritage of Puritanism, we Americans tend to think that if something is good for us, it also has to be difficult or bad tasting or time and labor intensive. In fact, once you have a little bit of knowledge, companion planting in one form or another is just as easy as any other kind of planting. To get that knowledge, seek out the gardening classic Carrots Love Tomatoes: Secrets of Companion Planting for Successful Gardening by Louise Riotte (Storey Books, 1998), which is available in paperback from major book retailers.