Companion Planting in the Vegetable Garden

Enlarge Image Image Gallery Lettuce, viola, tulips and parsley reside in harmony in this garden. Jerry Pavia

Did you ever notice that Mother Nature tends to garden using what seems to be randomly distributed mixtures of plant species? Or that ancient agriculturists tended to sow a hodgepodge of crops in the same field? Surely you’ve encountered the phrase, “three sisters,” which describes a kind of cropping where corn stalks support vining beans and squash or pumpkins shade out the weeds. No matter how you harvest it, companion planting in the garden has the capability to offer larger and more diverse yields with fewer fertility and pest problems. Here’s how.

Plants form relationships with their environment and the other life forms around them, whether that be other plants, insects, soil microbes or even the gardeners who nurture them. Some of those relationships can weaken the crop (think weedy lamb’s ears overtaking your onion patch), while others can strengthen it (three sisters, for example). Some would promote companion planting as a means to keep this or that pest away rather than how to make a garden ecosystem healthier, and therefore more productive. The fact of the matter is that if you avoid monocultural blocks in the garden and place certain species in close proximity of others, you will foil all kinds of pesky problems.

The mighty marigold

Take, for instance, the marigold. Although its insect repelling properties are legendary in even a beginning gardener’s vocabulary, the fact is often overlooked that it also plays a vital role as an attractor. Hoverflies, whose larvae are voracious eaters of pests like aphids and who as adults play an important role in the garden as pollinators, are attracted to the bright yellow and orange flowers.

Nasturtiums, too, are well-regarded for their natural repelling of pests like cucumber beetles, white-fly and, my personal nemesis, the squash bug, but they also are a strongly attractive plant. Planting nasturtiums, whose long vines curl in and out of the area around plants like zucchini, can help to greatly increase your yields from those plants by attracting significantly more insect pollinators than squash blossoms are able to alone — all the while keeping squash bugs at bay.

Atmospheric pressure

Plants also can directly benefit other plants in the garden, either through creating amiable microclimates, adding nutrients to the soil, or providing needed structure. Probably the most recognizable example of this is the “three sisters” gardening technique used by early Native American gardeners.