Companion planting is growing two or more crops near each other using the theory that improved pest management and reduced pesticide use enhances pollination and allows for higher vegetable yields.
Consider the following approaches to incorporate companion planting into your backyard vegetable plot.
Gardeners can enlist the aid of beneficial organisms such as ladybird beetles, lacewings, mantids, spiders and predatory mites in the battle against pest population by growing plants that create habitat for those beneficials near vegetables under siege.
Plants such as basil, cilantro, dill, fennel and parsley are among those that provide shelter and food for various life stages of predatory and beneficial parasites. In addition to attracting the natural enemies of garden pests, companion species are useful in luring and retaining pollinators in the garden. Plants such as buckwheat and clover are excellent choices for attracting bees to adjacent pollinator requiring crops with the added benefit of serving as weed-suppressing cover crops.
Companion planting, with its various pairings is best used with a greater objective in mind than merely positioning plants in relation to one another. Maintain diversity in the garden, as in nature, to protect health and productivity of a community of plants.
The classic example that comes to mind when many of us think of companion planting are marigolds grown in and around vegetable crops as a pest repellent (My mother and grandmothers believed this). Research has shown that the roots of African and French marigolds do produce biochemicals that are toxic to root nematodes, minute worm-like organisms that can kill plants or reduce yields. However, that benefit is reaped after growing marigolds as a cover crop and tilling them into the soil to release the chemicals. If you like them as I do, because I like their strong orange color in the garden, grow them — they add diversity.
One of the oldest examples of companion gardening is often referred to as the Native American “Three Sisters Garden.” The “Three Sisters” are corn, beans and pumpkin or squash planted together in groups or hills. Native American myths speak of three sisters who could not get along but are convinced to use their differences to help each other — so much so that they depend upon each other. Meals resulting from a Three Sisters garden — corn and squash for energy and beans for protein — provide delicious and nutritious dining.
How does each “Sister” benefit the others?
Nitrogen fixing legumes like beans are able to have a relationship with bacteria in soil, Rhizobium, that benefits both bacteria and beans. These bacteria form nodules on the Sister Bean roots. They are then able to take in atmospheric nitrogen — usually unavailable to plants — and convert it to a form that plants can use. This is good for the bacteria, the bean, squash and, especially, corn. Corn requires a lot of nitrogen to grow well and benefits greatly from the nitrogen-fixing beans.
What does Sister Corn contribute? Pole beans can climb the corn stalks. Also, the high canopy of corn foliage may confuse the adult squash borer and reduce the damage of this pest on the squash.
Finally, how does Sister Squash bless her two siblings? The broad spreading leaves of the squash vines provide living mulch for the corn and beans to reduce weeds and hold moisture. Prickly squash vines climbing corn stalks may deter raccoon invasion of the corn. There are several other important ways that companion plants help each other because of their proximity.
Trap cropping is the practice of planting something between the main crop that attracts a specific pest away from it. An example is planting dill among tomatoes. Tomato horn worms prefer the dill. Nasturtiums attract aphids and many other pests.
Are you interested? I have received so many questions on this subject, so I felt it warranted a column of its own. The number of rigorous scientific studies regarding companion planting is small compared to the number of books, lists and charts about companion planting based on anecdotal evidence.
Be mindful that choosing a companion planting scheme not grounded in science may result in disappointment. However, personal observations of effective plant groupings are useful as a starting point. Being able to replicate those observations over time and locations will confirm companion planting as a valuable gardening practice. Try combinations of your favorites that will benefit each other. We are in this together! Feel free to contact the Lincoln County Extension Office with your questions and comments.
Enjoy the journey.
For additional information or questions and the Master Gardener Program, contact Nebraska Extension, West Central Research and Extension Center at 308-532-2683.