The Best & Worst Companion Plants For Tomatoes (According to Science)

Companion planting is an age-old gardening practice that harnesses the natural relationships between plants to boost growth, deter pests, and enhance garden health. Supported by scientific insights, we discuss the best and worst companion plants for tomatoes. Discover how pairing tomatoes with the right companions can lead to healthier plants, increased yields, and a more resilient garden.

What Should You Plant With Your Tomatoes?

red ripe tomatoes grown in a greenhouse.

Companion planting is a gardening technique that involves growing different plants together to enhance each other’s growth, deter pests, and improve overall garden health. This practice leverages the natural relationships between plants to create a more productive and sustainable garden.

By strategically pairing plants, gardeners can reduce the need for chemical fertilizers and pesticides, improve soil fertility, and increase yields. Companion planting also helps to attract beneficial insects, promote pollination, and create a diverse and balanced ecosystem within the garden.

Understanding and utilizing companion planting can lead to healthier plants, more efficient use of garden space, and a more resilient and thriving vegetable garden.

Legumes

Young green peas grown in a garden.

Legumes can effectively control weeds in tomato cultivation without reducing crop yields by competing with them for resources, thus minimizing the need for manual weeding or herbicide use.

A meta-analysis revealed that legume companion plants had no significant impact on yield, but they reduced weed biomass by 42% and 56% respectively, when compared to weeded and non-weeded control treatments.

My favorite all-purpose legume companion — bush beans. Stick em’ everywhere and harvest them for your kitchen all summer long. Eat them freshly sauteed, pressure-can them, and even ferment them. I will plant green bush beans in every corner of every garden bed where they will receive enough sun to produce.

For nitrogen-fixing — soy, fava, and cowpeas are at the top. And you can eat them too.

Potato Onions

A field of grown white mustard.

Intercropping tomatoes with potato onions can alleviate the severity of Verticillium wilt. This companion planting enhances tomato disease resistance by influencing root exudates and upregulating defense-related gene expressions.

Verticillium wilt is especially serious in tomatoes, potatoes, and strawberries. Look for plants with wilting, yellowing leaves, often starting on one side. The disease also causes stunted growth and can be confirmed by cutting into the stem near the base to look for darkened rings, indicating vascular damage.

Potato onions resemble shallots and are a fantastic storage onion well adapted to cold Northern climes. All parts are edible and can be enjoyed like any other onion.

Marigold Flowers

Marigold flowers in a garden.

In studies, marigolds are shown to affect fruit quality positively and help control root-knot nematodes. They do this without competing for resources or decreasing tomato yield.

Marigolds are another one of those all-purpose companion plants that can benefit every plant and your entire garden overall.

Cucumbers

Freshly picked cucumbers in the hands of a woman.

Cucumbers and tomatoes can be excellent companions when grown together. Both plants enjoy similar growing conditions, including plenty of sunlight and well-drained soil. Cucumbers can benefit from the shade provided by taller tomato plants, which can help reduce the risk of heat stress. Cucumbers’ sprawling vines can act as a living mulch, suppressing weeds and retaining soil moisture around the tomato plants.

Growing these two crops together can optimize garden space, especially when trellising cucumbers to grow vertically. This combination supports healthy growth and high yields for both plants, making them a productive and efficient pairing in the garden.

Okra + Currant Tomatoes

Okra grown in a garden.

Okra and currant tomatoes make an excellent pairing in the garden. When okra is used as a support pole, it provides a sturdy structure for the vining currant tomatoes to climb. This vertical growing method saves space and enhances air circulation around the tomato plants, reducing the risk of fungal diseases.

Okra’s tall, robust stems offer strong support, while the tomato vines benefit from the increased sunlight exposure. Okra and tomatoes have similar soil and water needs, making them easy to manage together. This combination optimizes garden space and creates a healthy growing environment for both plants.

Basil

Basil grown in a garden.

Studies have shown that companion planting tomatoes with basil in greenhouses does not significantly decrease tomato productivity. Basil may also positively affect fruit quality and help control root-knot nematodes.

Numerous studies have also shown that basil masks the scent of the tomato plant and deters tomato and tobacco hornworms, yellow-striped armyworms, and thrips.

Basil is the classic companion that has gone hand-in-hand with tomatoes for decades, and science seems to back it up as extremely beneficial! Many top tomato growers insist that basil makes tomatoes taste better on the vine — not just in tomato sauce recipes.

Lettuce

Freshly harvested lettuce in the hands of a woman.

Lettuce is a fantastic companion plant for tomatoes because it grows quickly and has shallow roots that do not compete with the deeper-rooted tomatoes. Planting lettuce around tomato plants helps to keep the soil cool and moist, reducing the need for frequent watering. Lettuce also acts as a living mulch, suppressing weed growth and preventing soil erosion.

As lettuce matures and is harvested, it leaves behind a mulch-like layer that continues to benefit the soil and tomato plants. This mutually beneficial relationship enhances overall garden productivity and maintains soil health.

Related: Effortlessly Grow an Endless Salad Garden All Season Long

Clover

Clover.

Studies have shown that intercropping tomatoes with clover reduces the density of tomato fruit borer eggs and larvae. It also enhances the presence of natural enemies like predatory bugs and parasitism rates.

There are many types of clover. They work as beneficial companion plants by enhancing soil fertility and structure, producing many flowers to attract flower-visiting natural enemies of many common pests, and repelling insects by secreting phenolic compounds.

Eggplant

Eggplant grown in a farm.

Eggplant and tomatoes are members of the nightshade family, and they share similar growing conditions, making them compatible companions. Eggplants can serve as a secondary crop that uses the same garden space as tomatoes.

When planted together, they can deter pests like the Colorado potato beetle, which may target one plant over the other. Additionally, eggplants’ broad leaves provide shade, helping to retain soil moisture and protect tomato roots from excessive heat. This partnership maximizes garden space and promotes healthier plants and higher yields.

Winter Rye Grass

A field of winter rye grass.

Winter rye grass is an excellent cover crop and companion for tomatoes. It is sown in the fall and grows throughout the winter, providing numerous benefits to the soil. Winter rye grass improves soil structure, adds organic matter, and enhances soil fertility through its deep root system.

When used as a companion plant for tomatoes, it helps suppress weeds, reduces soil erosion, and retains moisture. In the spring, rye grass can be cut down and used as a green manure or mulch, enriching the soil with nutrients as it decomposes. This practice results in healthier tomato plants with improved growth and yield.

Buckwheat

Buckwheat blooming.
Photo Credit: Envato Elements.

Buckwheat is a beneficial companion plant for tomatoes, known for improving soil health and attracting beneficial insects. Buckwheat grows quickly, providing ground cover that suppresses weeds and prevents soil erosion.

Its extensive root system enhances soil structure and increases organic matter, promoting healthier tomato plants. Buckwheat flowers attract pollinators and beneficial insects such as predatory wasps and hoverflies, which help control pests that could harm tomato plants.

Buckwheat can be used as a green manure; when cut and turned into the soil, it adds valuable nutrients and organic matter. This practice improves soil fertility and supports robust tomato growth, making buckwheat a valuable ally in the garden.

Cowpeas

Black eyed peas placed inside a bowl.
Photo Credit: Envato Elements.

Cowpeas or black-eyed peas are great companion plants for tomatoes, primarily due to their nitrogen-fixing ability. These legumes have a symbiotic relationship with nitrogen-fixing bacteria, which helps enrich the soil by converting atmospheric nitrogen into a form that plants can use.

This process benefits tomatoes, which are heavy feeders and thrive in nitrogen-rich soil. Cowpeas’ sprawling growth habit also helps suppress weeds and retain soil moisture. Their presence in the garden can also attract beneficial insects that prey on tomato pests, creating a healthier growing environment. This partnership enhances soil fertility and promotes robust tomato growth, increasing yields.

Living Mulches

A field of white clover planted as a living mulch.

Living mulches, such as clover, vetch, or alfalfa, are excellent companion tomato plants. These low-growing plants cover the soil surface, providing a natural mulch that helps retain moisture, suppress weeds, and reduce soil erosion.

Living mulches also enhance soil fertility by fixing nitrogen and adding organic matter as they decompose. When used with tomatoes, living mulches create a more balanced microenvironment, improving soil health and reducing the need for chemical fertilizers. This symbiotic relationship leads to stronger, more resilient tomato plants with better fruit production.

More Tomato Growing Tips

Tomatoes grown in a garden.

Learn More: 15 Secrets To Growing Killer Tomatoes This Season

Benefits of Mulch

Tomatoes.
Photo Credit: Envato Elements.

Learn More: Secrets of Mulching For Your Best Tomato & Pepper Harvests

Sources & Further Reading on Companion Planting

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