Seasoned gardeners have determined that certain plants improve the growth of tomatoes by repelling insect pests and tomato plant diseases, while others are best kept at a distance. Learn which herbs, flowers, and root vegetables make the best (and worst) tomato companion plants.
What Is Companion Planting
Companion planting is also known as interplanting, intercropping, or creating a polyculture. It is the practice of partnering plants so they gain mutual benefits from growing near one another or from succession planting (staggering crop plantings). The benefits of companion planting include pest control, weed reduction, and disease prevention. Some plant partnerships can enhance soil and attract pollinators. Applying companion planting practices in your tomato garden will help manage damaging pests that are attracted to this vegetable.
Best Tomato Companion Plants
What grows best next to tomatoes? Here are recommended companion plants—both best plants and beneficial plants—that can improve the health and flavor of tomatoes, and include the following herbs, flowers, and root vegetables. Some plants are used as standard crops and others are used as cover crops (grown solely to improve the soil, prevent erosion, and act as mulch).
Best Companion Plants
Sweet Basil: Basil is an important tomato companion plant because the herb repels insects, improves growth, and enhances flavor. Basil also repels mosquitoes and flies (even fruit flies). Bush beans: Short plants like bush beans help tomato plants in an unusual way; this plant increases the air circulation around tomato plants, eliminating any damp and humid conditions from developing that would attract spores. Bush beans also attract bumble bees. Clovers: Crimson clover and red clover help tomatoes in various ways. Both plants provide nitrogen to the soil. In addition, they both deter weed growth and attract pollinators like bumble bees and other beneficial insects. Collard Greens: Plant collard greens a few feet away from tomatoes to lure away damaging harlequin bugs, but consider them sacrificial plants that can’t be harvested. Cowpeas (Black-Eyed Peas): Also called black-eyed peas, cowpeas act as a lure for the southern green stink bug, which loves to feed on many plants, including tomatoes. Cucumbers (Gherkins):This classic standard crop thwarts the germination of weed seeds because the plant’s ground cover hinders sunlight from reaching them. However, many gardeners prefer to keep cucumbers away from tomatoes because they can share the same diseases, such as mosaic virus and phytophthora blight. Culinary dill, oregano, and cilantro (coriander) (wild marjoram): These herbs are other important companions that encourage beneficial bugs to stay and eat pests and parasitic bugs that damage tomato plants. Mustard greens: Plant mustard greens only as a cover crop and mix the greens into the soil before planting tomatoes to reduce verticillium wilt, a common problem for tomato plants. Oat and winter rye: These grasses are great allies for tomato plants because they control weed growth. Weeds can’t grow through the oat’s matting and winter rye greatly reduces weed growth by hindering seeds from germinating. Radishes (rabones): Plant radishes right near the bases of tomatoes as sacrificial plants used to stop flea beetles from attacking tomatoes. Common sunflowers and coneflowers (such as echinacea) : The cheerful flowers are favorites of bumble bees that pollinate tomatoes. Sweet alyssum. The flowers feed good bugs (like parasitic wasps) that eat pests such as aphids. Thyme varieties: This herb is specifically helpful in reducing the egg-laying efforts of adult armyworms, especially the yellow-striped armyworm most prevalent in the eastern part of the U.S.
Other Beneficial Plants
Amaranth (tassel flower): This plant helps repel pests by attracting predatory beneficial insects. Borage (Starflower): This plant improves growth and flavor and repels tomato hornworms. Bee balm, chives, mint, lemon balm, and parsley: These herbs improve health and flavor. Be careful when companion planting bee balm, lemon balm, and mint, as they can become invasive. Carrot roots: Plant carrots near tomatoes to help loosen soil. If planted too closely, the carrots may not get as large as they should, but they will still taste good. Garlic varieties: This plant repels red spider mites. Garlic sprays help control late blight. Garden lettuce: Lettuce benefits from being planted in the shade of taller tomato plants, but it provides a living mulch—helping to keep the soil cool and moist. Marigold flowers: French marigolds are small companion plants that grow well with tomato plants in containers. Marigolds are beneficial because the flower repels pests and reduces root-knot nematodes in soil. Nasturtium flowers: This flower not only looks lovely planted with tomatoes, but it also serves as a trap crop for aphids. Plus, it’s an edible flower, making a pretty—and tasty—addition to salads.
Worst Tomato Companion Plants
These plants are infamous for inhibiting tomato plant growth and increasing their susceptibility to pests or diseases and should not be planted with tomatoes.
Cabbage (Brassica) family: Relatives of cabbage cultivars stunt the growth of tomato plants (including broccoli, Brussels sprouts, cabbage, cauliflower, collards, ornamental kale, kohlrabi, rutabaga varieties, and turnip). However, some gardeners do like placing collard greens a few feet away from their tomato plants to lure away damaging harlequin bugs. Sweet Corn: The corn earworm is the same as the tomato fruitworm (Helicoverpa zea). Growing plants in proximity that are susceptible to the same pests can invite disaster and a decimated garden. Eggplant, hot peppers, and heirlom potatoes: These plants are in the nightshade family like tomatoes, and are all susceptible to early blight and late blight, which can build up in the soil and get worse each year. Avoid planting them near each other or in place of each other for at least three years. Tomato hornworms (Manduca quinquemaculata, the larva stage of the five-spotted hawkmoth) love the foliage and fruit of tomatoes, peppers, and eggplants and can quickly decimate plants. Also, planting tomatoes near potatoes can make the potatoes more susceptible to potato blight. Fennel: Fennel secretes a substance from its roots that inhibits tomato plant growth. This secretion affects many other garden plants, too. However, some gardeners deploy fennel to manage aphid invasions. Walnuts: Do not plant tomatoes under walnut or butternut trees, which produce an allelopathic chemical called juglone that inhibits the growth of tomatoes (and all the members of the nightshade family). Tomatoes are also susceptible to the disease walnut wilt.
If you can’t plant tomatoes among your roses, make a spray of liquefied tomato leaves, a tablespoon of cornstarch, and about 4 pints of water. Spritz your roses once a week to keep black spot at bay.
