Companion planting is a horticultural technique where specific plants are grown near each other to encourage a mutually beneficial relationship. Cherry tomatoes are excellent candidates for this strategy because they are heavy feeders and susceptible to various common garden pests. By carefully selecting companion plants, growers can create a miniature ecosystem that naturally enhances the health and productivity of the tomato plant. This practice leverages natural biological and chemical interactions to support vigorous growth and fruit production.
Companions That Attract Beneficial Insects
Introducing flowering plants near tomatoes creates a habitat for beneficial insects that function as natural pest control. Dill produces umbel-shaped flowers highly attractive to parasitic wasps, such as the braconid wasp. These wasps are natural enemies of the destructive tomato hornworm, laying eggs inside the caterpillar to kill the pest.
Borage is a valuable companion, featuring small, star-shaped blue flowers that draw in pollinators and beneficial insects, including bees. Bees aid in tomato flower fertilization, and borage is also thought to deter tomato hornworms. Flowers like sweet alyssum and calendula provide nectar and pollen, supporting populations of hoverflies and ladybugs. Ladybugs are effective predators, consuming soft-bodied pests like aphids and feeding on hornworm eggs.
Companions That Repel Pests
Many herbs and flowers deter harmful insects by releasing strong scents or chemical compounds. Basil is a popular companion because its pungent aroma masks the scent of the tomato plant. This makes it harder for pests like the tomato hornworm moth and whiteflies to locate their host, and some studies suggest basil may also deter thrips.
The strong odor of alliums, such as garlic and onions, repels pests including spider mites and various moths. Planting a border of chives creates a fragrant barrier that confuses pests relying on scent to find the tomato foliage. French marigolds are known for combating root-knot nematodes, which are microscopic worms that attack plant roots. Certain varieties release a chemical compound through their roots that suppresses these soil-dwelling pests.
Companions That Provide Growth Support and Soil Health
Some companion plants offer physical and chemical benefits that directly enhance the tomato’s growing environment. Legumes, including bush beans and various clovers, are crucial for soil fertility. They host nitrogen-fixing bacteria in their root nodules, which convert atmospheric nitrogen into a usable form. This process helps replenish the nitrogen that cherry tomatoes quickly deplete.
Low-growing plants like lettuce, parsley, and spinach function as living mulches when planted around the base of the tomato plant. Their foliage suppresses weeds that compete for water and nutrients, and they shade the soil. This shading effect keeps the soil surface cooler and helps retain moisture. Retaining moisture is beneficial for the tomato’s shallow root system during hot weather. Root vegetables like carrots and radishes, with their deep structures, help break up compacted soil, improving aeration and water penetration for the tomato’s roots.
Plants to Never Grow Near Cherry Tomatoes
Certain species should be avoided because they compete too aggressively or pose a disease risk. Plants in the Brassica family, such as broccoli, cabbage, and cauliflower, are heavy feeders that demand large amounts of soil nutrients. Planting them close to tomatoes creates direct competition for resources, which can stunt the growth and reduce the yield of the cherry tomato.
Other members of the Solanaceae (nightshade) family, including potatoes and eggplants, should be kept separate. These plants share a susceptibility to the same soil-borne diseases, such as early and late blight. They also attract common pests like the tomato hornworm, increasing the risk of widespread infection. Fennel is a poor companion for nearly all garden vegetables because it releases substances that inhibit the growth of surrounding plants. Mature dill plants can also stunt tomato growth, so they should be harvested before reaching full maturity near the tomato base.