Companion planting is the practice of grouping plants together that have beneficial relationships. The goal of companion planting is to increase the yield of plants by controlling for pests, increasing the nutrients within the soil, and increasing pollination. It should be noted that companion planting is not an exact science, and takes experimentation and observation.
A well-known example of this practice is the “Three Sisters” garden, consisting of maize, beans, and squash. Various Native American tribes discovered this practice thousands of years ago. Planting these three crops together increases the yields of all three plants. The beans are legumes, which increase the nitrogen content of the soil through the nitrogen-fixing bacteria contained within their roots. The squash’s large leaves shade the ground and retain moisture in the soil. The maize provides a tall stalk for the bean vines to climb up and reduces the competition on the ground for space to grow.
Companion planting mimics nature by incorporating a variety of plants into one location. Plants often develop symbiotic relationships after adapting and evolving together. By separating crops, we are limiting the natural benefits these plants have developed in nature. Monoculture, or the practice of planting a single crop, corrodes the soil and reduces the nutrients over time.
Companion Planting with Vegetable Crops
There are hundreds of beneficial combinations for vegetable crops. Here is a quick summary of the main groupings:
Legume family plants, such as peas and beans, should not be planted in proximity to plants in the allium family or garlic crops. Onions and garlic can stunt the growth of peas and beans. Legumes pair well with the Brassicas family, carrots, lettuces, spinach, strawberries, corn, and cucumbers.
The Brassicas family, such as broccoli, cauliflower, and cabbage, grow well with beans, carrots, lettuces, onions, spinach, and most herbs. They do not grow well with strawberries, tomatoes, peppers, and squash.
The Allium family should be planted with potatoes, carrots, lettuces, tomatoes, strawberries, and the Brassicas family. These crops do not pair well with legumes.
Place potatoes with onions, corn, lettuces, beans, and the Brassicas family. Potatoes do not grow well with tomatoes, pumpkin, squash, and zucchini.
Lettuces and spinach both grow well with carrots, radishes, the Brassicas family, onions, strawberries, and cucumbers.
Tomatoes love being paired with basil, nasturtiums, marigolds, onions, and cucumbers. Don’t plant tomatoes with potatoes, corn, or the Brassicas family.
Most herbs can be placed together or amongst other vegetable crops. However, be careful placing dill with carrots and tomatoes.
Another important aspect of companion planting is the placement of pest-repelling plants in your vegetable gardens. Not all insects are bad, but some can eat away your garden. Plants that have pest-repelling properties include marigolds, alliums, and several varieties of herbs.
Marigolds deter nematodes, which can attack the roots of plants. Herbs such as basil kill mosquito eggs, and rosemary keeps away both flies and mosquitoes. Mint deters ants, mice, flies, and mosquitoes (although it must be potted because it is an aggressive grower). The allium family keeps away slugs, carrot flies, aphids, and cabbage worms.
Incorporate local, pollinator-friendly plants into your vegetable garden. Pollinator plants support local pollinators such as bees, butterflies, moths, and hummingbirds. Increasing the number of local pollinators in your garden will increase the yield from your vegetable-producing crops.
Research which pollinator plants are the native to your area, but common ones include Purple Cone-Flower (Echinacea), Yarrow varieties, Goldenrod, Black-Eyed Susan, Salvias, Penstemons, Blanket flower, Borage, and Aster.
Temperature and Sunlight Variance
Plant crops that require similar temperatures and sun exposure together. For example, cool-weather crops, such as kale, lettuce, spinach, and broccoli, should be planted together in areas that are shadier and have lower temperatures. On the other hand, warm-weather crops, such as peppers, tomatoes, zucchini, and squash, should be planted together in areas that receive increased sun and higher temperatures.
Keep in mind that the northern and eastern areas of the garden typically receive decreased sunlight and temperatures, while the southern and western areas of the garden typically receive increased sunlight and temperatures.
Photo by Krista Bratvold
Krista Bratvold travels North America in her converted van to raise awareness for sustainable living and protection of our lands. She is a landscape photographer and travel writer who educates on sustainable food production and native plants. Connect with Krista at The Suitcase Photographers and on Instagram @thesuitcasephotographers. Read all of her MOTHER EARTH NEWS posts here.