Companion planting is the practice of growing different plants together for mutual benefit. The research on the benefits of planting certain crops together focuses on vegetable gardens, but ornamentals like roses can also benefit from knowing compatible plants to help prevent disease and insect infestation.
Unlike other areas of gardening, this type of gardening is not always based on hard scientific facts but on observations, the type of garden lore found in farmer’s almanacs. There is always an element of trial and error to see what works for you. However, understanding your garden as a system of biodiversity where plants are all connected and interdependent on each other helps you make better plant choices. Read on for a chart with recommended companion planting choices and other tips for popular garden crops.
What Is Companion Planting?
Companion planting is best defined as the practice of planting different plant species in close proximity so that they can offer identifiable benefits to one another. Sometimes the benefit is one-sided, with one plant selflessly offering most of the partnership advantages to the other. In other cases, the benefit is mutual, with each plant enhancing the other's health or vigor.
Benefits of Companion Planting
There are numerous benefits to companion planting. Plants can attract beneficial insects and pollinators, deter pests, and act as insect repellants. They can fend off predators and undesirable wildlife. Raccoons, for instance, dislike the smell of cucumbers.
Plants also play a role in soil fertility by improving the nutrient supply, availability, and uptake from the soil. Tall plants such as corn can provide shade for crops like lettuce which does not do well in the hot summer sun, and they can serve as support for crops that need trellising. Interplanting different crops can help mark garden rows, and distinguish fast germinating plants like radishes from slower germinating plants like lettuce. Proper companion planting can even help suppress weeds.
Companion Planting Chart
Before you even start thinking about companion planting in your garden, make sure that you follow the rules of crop rotation. Don’t plant the same garden crop in the same spot for consecutive gardening years, as this can lead to pest and disease problems, as well as nutrient imbalances.
Depending on the source you consult, information on which plants make good companion plants for each other can vary greatly. There are only a few “hard facts” that are unanimously and universally agreed upon, such as the benefits of planting corn, pole beans, and pumpkins together. The corn provides support for the beans which pull nitrogen from the air to benefit the corn's roots. The pumpkins thrive in the dappled shade of the corn and suppress weeds and keep the ground cooler to conserve water.
Here is a list of popular garden crops with their anecdotal recommended companion plants:
|28 Garden Crops||Companion plants|
|Asparagus||Calendula, Petunias, Tomatoes|
|Basil||Peppers, Purslane, Tomatoes|
|Beans||Broccoli, Cabbage, Carrots, Cauliflower, Corn, Cucumbers, Eggplant, Garden peas, Potatoes, Radishes, Squash, Strawberries, Tomatoes|
|Beets||Brassicas, Bush beans, Garlic, Lettuce, Onion family|
|Broccoli||Oregano, other Brassicas (cabbage, brussels sprouts, cauliflower, etc.)|
|Brussels sprouts||Basil, Beans, Beet, Carrot, Garlic, Mint, Nasturtium, Onion, Peas, Thyme|
|Cabbage||Other cole crops (broccoli, Brussels sprouts, Collard greens, Kale, Kohlrabi, Rutabagas, Turnips), Onions, Potatoes|
|Carrots||Chives, Leeks, Onions, Peas, Radishes, Rosemary, Sage|
|Cauliflower||Beans, Beets, Broccoli, Brussels sprouts, Celery, Corn, Onions, Radish, Spinach, Cucumber|
|Corn||Beans, Cucumbers, Garden peas, Melons, Potatoes, Squash|
|Cucumber||Beans, Beets, Corn, Onions, Garden peas, Radishes|
|Dill||Broccoli, Brussels sprouts, Cabbage, Corn, Cucumber, Lettuce, Onion|
|Eggplant||Beans, Catnip, Marigold, Peas, Pepper|
|Garlic||Beets, Carrots, Cole crops, Eggplant, Peppers, Potatoes, Tomatoes|
|Kale||Beet, Beans, Celery, Cucumber, Dill, Garlic, Lettuce, Mint, Onion, Peas, Pepper, Potato, Rosemary, Sage, Spinach|
|Lettuce||Corn, Pumpkins, Radishes, Squash|
|Onions||Beets, Carrots, Cole crops, Lettuce|
|Peas||Beans, Carrots, Corn, Cucumbers, Eggplant, Peppers, Radishes, Spinach, Tomatoes|
|Peppers||Basil, Onions, Okra|
|Potatoes||Beans, Cole crops, Corn, Lettuce, Spinach, Radishes|
|Radishes||Chervil, Lettuce, Nasturtium, Peas|
|Rosemary||Beans, Broccoli, Brussels sprouts, Cabbage, Carrot, Cauliflower, Kale|
|Spinach||Beans, Cilantro, Eggplant, Oregano, Peas, Rosemary, Strawberries|
|Strawberries||Borage, Bush beans, Caraway, Chives, Lettuce, Onions, Sage, Spinach, Squash|
|Tomatoes||Basil (and other herbs); Carrots, Cucumbers, and Squash (as part of a three-way companion partnership)|
|Watermelon (and other melons)||Broccoli, Corn, Garlic, Radishes|
|Winter squash (including pumpkins)||Beans (pole), Buckwheat, Calendula, Corn Marigold, Nasturtium, Oregano|
|Zucchini (and other summer squash)||Beans, Corn, Garden peas, Radishes|
Best Companion Plants
Some vegetable combinations are superstars in bringing out the best in one another, or in preventing common pest and disease problems. Among these outstanding combinations:
- Corn, pole beans, and squash: Known as the "three sisters," this combination was first developed by American Indian people centuries ago. Corn, with its sturdy stems, provides upright support for climbing beans. for their part, the pole beans fix nitrogen in the soil, providing essential nutrients for all three sisters. And the large leaves of the ground-dwelling squash shade the soil, retain moisture, and block out weeds.
- Cucumbers, sunflowers, and pole beans: The principle here is the same as for the three sisters: the sunflower provides support for climbing pole beans, while cucumber vines shield the ground.
- Basil and tomatoes: These can be considered "best friends" in the garden. Basil repels thrips and disrupts the habits of the moths that cause tomato hornworms.
- Sage, with carrots or cabbage. Sage is a proven repellant for carrot flies and cabbage moths.
- Parsley and tomatoes: Parsley attracts beneficial insects that help keep control of damaging insects that prey on tomato plants.
In addition, there are some plants that offer benefits to almost any plant they are paired with—either by repelling damaging insects or attracting beneficial insects that prey on the bad guys. These champions include:
- Nasturiums: This plant lures hungry caterpillars away from brassicas, including cabbage, broccoli, and kale,
- Mint: This plant has an odor that strongly repels aphids, ants, and flea beetles.
- Garlic: This onion relative has a strong scent that is repugnant to aphids and all repels a variety of mites, moths, and beetles.
- Dill: This plant is known to attract ladybugs, which are voracious eaters of damaging aphids and spider mites.
Companion Planting with Herbs
Not every garden is large enough to grow a variety of crops for companion planting. But that does not mean that you cannot take advantage of the numerous benefits that herbs offer like trapping and repelling pests and attracting pollinators and other beneficial insects to increase the biodiversity in your backyard.
Allow some of the herbs to bloom because that’s when they become a real magnet for beneficial insects.
Flowers as Companion Plants
Planting flowers in your vegetable garden does more than create beauty and provide cut flowers. Annuals such as nasturtiums, sunflowers, marigolds, and zinnias, and perennials such as lavender repel pests and attract beneficial insects.
Companion Planting Mistakes to Avoid
Just as there are plants that make good neighbors, there are plenty of opportunities to plant bad neighbors. Generally, plants that compete because of similar nutrient needs, water, space—aboveground growth and belowground root systems—as well as sunlight should not be planted next to each other.
Crops that are susceptible to the same plant disease, such as blight, should be kept as far as possible from each other to prevent it from spreading. The same applies to pests.
Some crops can inhibit the growth of other plants. Fennel is often offered as an example of a poor companion plant that should be given its own spot in the garden far away from all other crops.