In The Garden With KokHeong: Companion Planting

Los Alamos

One way I get the most out of my garden is employing the technique of companion planting, which is a form of polyculture involving growing certain plants close together so that they help one another produce more. This can be in the form of one plant supplying certain nutrients in the soil that the other plant needs, deterring pests that the other plant is susceptible to, attracting beneficial pollinators for its companion, or simply providing shade or a physical protection to the companion plant. Companion plants don’t compete with one another for soil nutrients or atmospheric conditions, so they can be planted closer together to maximize growing space.

Conversely, certain plants growing close together adversely affect one or the other. I avoid planting onions and garlic (or other members of the allium family) next to peas and beans (or other members of the legume family). The peas have been observed to grow poorly and can reportedly acquire an onion taste.

A google search on “companion planting” will show up some nifty charts indicating which plants are suitable for companion planting and which combinations are to be avoided. They can be printed out for quick references.

For thousands of years, Chinese farmers have planted mosquito ferns in their rice fields to increase yield. Although the ferns are considered to be an invasive species of aquatic weed here in the United States, they are hosts to a bacterium that fixes nitrogen from the air, and their proliferation keeps the rice paddies weed-free, provides nitrogen to the rice plants, and acts as a sustainable fodder for livestock.   Another good example of companion planting is the “Three Sisters” system (see photo) consisting of corn, bean and squash growing close together, a technique that originated from Native American practices. Corn is planted first in the middle of a mound of dirt. When they are about 8-10” tall, the beans are planted around them. The corn stalks provide supports for the beans to climb. Squashes are planted last, after the beans are established, by which time the ground is warm enough for them. They keep down the weeds, fortify the dirt mound that holds the corn and beans together, and make the most use of the horizontal growing space not needed by either the beans or the corn. Their prickly leaves and stems deter small rodents from devouring the beans and corn. The beans meanwhile fix nitrogen in the soil and make it available for the other two “sisters.”

I plant perennial and annual herbs for reasons beyond culinary. Many of them are wonderful companion plants for my other vegetables. I particularly like having mint, borage, thyme, tarragon, oregano, sage, dill, parsley, cilantro, and fennel scattered around the garden to deter a wide variety of pests like cabbage worms, tomato hornworms, beetles, squash borers, and others. Not only do their flowers look and smell good, they also attract pollinators to my garden. In particular, dill, cilantro, and fennel lure ladybugs from my neighbors’ gardens into mine! I like growing flowers like nasturtiums, marigolds, and calendulas not only for their long-lasting blooms but also to keep harmful bugs at bay.  A common practice of companion planting is sowing a mix of carrot and radish seeds together. The radishes germinate first, breaking up the soil as they grow, to allow carrot seeds to establish themselves. After the radishes are harvested, the carrots continue to grow in the same spots, their roots taking advantage of the loosened soil and spaces previously occupied by the radishes.

I’m not quite sure why, but planting certain vegetables next to one another enhances their flavors. For example, chives are known to sweeten carrots, while basil is thought to make tomatoes sweeter. Although I can’t vouch for the former claim, I believe the latter claim is actually a reasonable one. Basil keeps certain pests away from the tomato plants, creating healthier tomato plants which are more likely to produce healthier fruits.

Choosing tall plants to provide shade for shade-loving plants like lettuces and spinach will keep them from bolting too soon. I sometimes put a few lettuce plants underneath a fruit tree or a berry bush and let them go to seed so I can have fresh lettuce late into the fall and early spring the next year.

 Have you experimented with companion planting in your own garden?