Current research-based evidence supports the historical gardening practice of companion planting. It was practiced in North America by the Five Nations Native People in a system called the “Three sisters.” Corn, beans and winter squash were planted together. The maize provides support for the beans which in turn provide nitrogen for the maize. The winter squash shaded the ground to retain moisture and suppress weeds. There are many groups of plants that interact symbiotically.

There are companion plantings that favor ornamental flowers and shrubs, but this article will focus on the vegetable garden.

One of the best things about companion planting in the vegetable garden is that it introduces flowers and herbs that would otherwise go unused. In this way, the vegetable garden is transformed from straight rows of beans, tomatoes, etc. to an interesting, joyful plot of diverse colors, textures and smells.

There are many benefits of companion planting. Peas and beans provide nutrients for other plants. These legumes have buds on their roots that contain nitrogen-fixing bacteria that provide food for other plants. Corn and green leafy vegetables require higher concentrations of nitrogen than many other plants.

Vegetables are classified as flowering plants and flowering plants require pollination to produce fruits and seeds. Some flowering plants are much better at attracting pollinating insects than others. If we plant these pollinator attractors next to plants that are not good at attracting pollinators, they will naturally benefit from increased pollination. Many of the herbs such as borage and all the common herbs (dill, parsley, fennel etc.) are powerful attractors and planting them near beans, peas, tomatoes and peppers will improve pollination leading to greater yields.

Another benefit of companion planting is pest control: First, some plants repel certain insects that damage vegetables. Aphids, for example, are repelled by any member of the onion family, especially garlic. Second, some plants attract insects that attract the bugs from vegetable plants. Third, some plants attract “good bugs”what eats the “bad bugs” who eats vegetables.

Tall plants such as sweet corn and sunflowers can function as a living trellis for vines and climbing plants. Two plants that can be sown together for this purpose are cucumbers and sunflowers.

As spring heats up into summer, it is possible to extend the growing season for some cool-weather crops by planting them in the shade of more heat-tolerant plants such as zucchini or green beans. This creates a microclimate where lettuce and spinach can survive. Companion plants build a system of biodiversity in your garden. It becomes its own ecosystem that can survive adverse conditions comparable to larger diverse and self-sustaining ecosystems.

Here are several beneficial companion plants:

First, tomato plants surrounded by basil and marigolds taste better and are less likely to be eaten by bugs or plagued by disease. Aphids love all kinds of garden vegetables but they HATE garlic. Scattering garlic plantings around your garden is beneficial for the whole garden.

Second, radishes used as row markers for slow germinating crops such as carrots and parsnips. These fast-growing roots mark the row where the slow-growing roots or parsnips are planted and help loosen the soil around the roots and parsnips.

Third, spinach and lettuce planted in your garlic patch benefit from aphids’ aversion to garlic. They also make efficient use of space and help control weeds by preventing sunlight from reaching the soil to germinate weed seeds.

A few more pairings: beets, cabbage and lettuce with onions; nasturtiums, zucchini and winter squash; spinach along the bottom of a trellis of peas will benefit from some shade and the nitrogen fixation by the peas; bush beans provide nitrogen for potatoes and cilantro is great for pest control.