Tomato Companion Planting: What to Plant With Tomatoes

Planting tomatoes comes with a host of possible setbacks, from blossom end rot to fungal diseases; insect pests like tomato hornworms, aphids, and whiteflies; early and late blight. Pruning, vigilant weeding, and mulch can help protect and manage plants until it’s time to harvest, but choosing the best tomato companion plants can do a lot of the work naturally.

Most wisdom around companion planting is anecdotal, but these are some of the tried and true partners for tomatoes:

• Basil. Basil and tomatoes are soulmates on and off the plate. This vibrant, aromatic herb repels insects, specifically flies and hornworms, and is believed to improve yield.
• Parsley. Parsley is another classic pairing: It boosts growth and attracts predators of the tomato hornworm, like ladybugs, but be sure to keep it well away from mint.
  
• Garlic. Garlic is said to repel spider mites, and a spray made with garlic can protect plants and soil against blight.
• Borage and squash. Tomatoes, borage, and squash are a common trio in companion planting, and that’s mostly due to timing. Borage, a flowering herb with blue star-shaped blossoms, is a big favorite of pollinators in general, and it also repels tomato hornworms. Not only does it improve the growth and flavor of tomatoes as it protects them, it makes an attractive, striking garnish, too. Then, by the time late-summer squash (which requires pollinators to fruit) is ready to blossom, the foundation’s already been laid.
• French marigolds and nasturtiums. Marigolds (not to be confused with the edible, decorative calendula, or pot marigold) and nasturtiums are particularly excellent companions for tomatoes. Marigolds have been shown to dispel root-knot nematodes, parasites that feed off of the nutrients in a tomato’s root system, and nasturtium acts as a general pest repellant thanks to its peppery, bitter oils—but don’t let them get too close. Nasturtium sprawls rapidly and can overtake other plants if not controlled.
• Asparagus. Asparagus illustrates the give and take of good companion planting: Tomatoes repel asparagus beetles with a chemical called solanine, and asparagus help to clear the soil of root-knot nematodes attracted to tomatoes.
• Chives. Not only are chives an essential allium in any herb garden, they repel aphids, nematodes, and mites.

In general, it’s good to consult a companion planting guide when planning a vegetable garden layout in any season: It will also highlight what not to plant as neighbors—tomatoes don’t play nice with anything in the cabbage (brassicaceae) family, for example, as cauliflower, kale, Brussels sprouts, and kohlrabi will stunt the plant’s growth.

The relationships aren’t always logical: Carrots are beneficial to tomatoes, but fennel, a relative of the carrot, is not. Fellow members of the nightshade family, like eggplant, are susceptible to the same diseases as tomatoes, early and late blight. This will take a toll on the soil, making it harder to prevent the next year.

Grow your own food with Ron Finley, the self-described "Gangster Gardener." Get the MasterClass Annual Membership and learn how to cultivate fresh herbs and vegetables, keep your house plants alive, and use compost to make your community - and the world - a better place.