In a world of monocrops and monoculture, the age-old gardening technique of companion planting — the practice of arranging symbiotic plants in close proximity to one another — is more important than ever. Whether you have a small balcony with a few veggies in containers or several raised beds overflowing with foliage, companion planting is an easy method that anyone can use to safely deter pests, increase yields and beautify their space.

Integrated Pest Management

Some plants exude chemicals from their roots, leaves and other parts that naturally deter pests and, in turn, make ideal neighbors to more vulnerable crops. This biochemical insect repellent is the essence of companion planting. But there are many other reasons to use this gardening practice.

For the organic urban farmer, companion planting is a way to provide diversity in the garden, mirroring the diversity of flora and fauna found in nature. In this way, companion planting helps to attract beneficial insects, birds and pollinators to the garden and offers them a wealth of variety in food sources. Furthermore, the practice of companion planting reduces the need for chemical pesticides because it eradicates the abundance of a single crop. When crops are intermixed, the insects that prey on just one plant will not be able to find (and demolish) it as easily. Your crops will be masked by the array of foliage around them, confusing the “bad bugs” in the process.

When planning your garden in late winter or early spring, take inventory of how many plants of one crop you may grow. Should the garden scheme include an abundance of one cultivar — let’s say tomatoes — opt to plant half of them to one side of the garden and the rest in another location. Then, interplant those with compatibles, such as asparagus and garlic (see chart for more). This way, your main crop is not in one easy-to-find spot and has the added advantage of the insect-repelling aromatics of its neighbors.

Also consider the addition of flowers as companions in the vegetable patch. Many flowers are quite effective at attracting beneficial insects with their source of pollen and nectar, and can give off a strong aroma, deterring other insects from your edibles. Similarly, use herbs for their potency as well, interspersing them with vegetables throughout the garden. Fennel, dill, yarrow and goldenrod will attract beneficials, such as bees, parasitic wasps and ladybugs, some of which will prey on the insect’s intent on consuming your vegetable plants.

Physical and Spatial Interaction

While companion planting is traditionally successful on a biochemical level, physically placing crops as they would benefit from others will increase your yields and extend your growing season, too. Consider how each variety grows, how much light it needs and its spacing requirements when laying out your garden.

Each year, I try to place my spring lettuces and other shade-loving greens in the shadow of taller crops, such as staked tomato plants or sweet peppers. Also called “nurse cropping,” these larger crops can provide protection and windbreak for smaller or more fragile cultivars and lengthen their growing season.

The (Other) Three Sisters

Squash (butternut and acorn), corn and beans, a group of vegetables also known as “the three sisters” in traditional Native American agriculture, is perhaps the best example of successful companion planting. When grown together, the three crops mutually benefit one another. The corn provides a trellis for the beans to grow on. The beans stabilize the corn and return nitrogen to the soil, increasing fertility for future years’ growth. The squash, when grown below the corn, acts as living mulch, shading the area beneath, preventing weed growth and retaining moisture in the soil. The squash’s spiny foliage also repels pests on a non-chemical level, insuring that bugs don’t build up a resistance.

If you’re new to companion planting, however, an easy place to start is with liberal use of the following three crops, which I call the “other three sisters.” Use these three anywhere in the garden as their companions are plentiful:

Mint: A pleasant-smelling but unruly crop, plants in the mint family (especially catnip) will deter aphids and cabbage moths and are medicinal to boot. But because mint will spread quickly and take over any free bit of soil, opt to grow it in containers and strategically place around the garden. If you prefer to have mint in closer proximity to your crops, transfer it to a plastic pot, and then burry the container up to the rim in the soil to contain the roots.

Marigolds: The strong aroma of these flowers has long been effective at deterring pests in the garden, so plant them generously throughout your veggie beds. At the end of the season, allow the flowers to dry and harvest seeds from your favorite and most effective varieties for planting in the following year.

Sweet Basil: Chances are, you’re probably already growing basil in your garden, but in case you’re not, I hope to change your mind. Sweet basil repels aphids, asparagus beetles, mosquitoes and mites, and stunts the growth of milkweed bugs. It also repels the tomato hornworm and is said to improve the taste of tomatoes. In some instances, sweet basil can act as a fungicide, and in all instances, it makes a mean pesto (are you convinced yet?).

Companion planting is an easy technique to employ in virtually any garden, and the benefits in pest management and yield are well worth the small bit of extra planning that goes into the process. Finally, don’t underestimate the visual appeal of companion planting — a mix of flower colors, foliage shapes and leaf textures adds a bit of whimsy that can’t be beat.

Companion Planting Guide