Best Companion Plants for Tomatoes

Basil – The Classic Tomato Ally

Basil is perhaps the most famous companion plant for tomatoes, and for good reason. This aromatic herb doesn’t just taste great alongside tomatoes in recipes like caprese salad—it actively supports their growth in the garden. Basil’s strong scent is known to repel common tomato pests such as aphids, whiteflies, and tomato hornworms. Its presence also appears to enhance the flavor and aroma of ripening tomatoes, a phenomenon observed by many gardeners over generations. Basil thrives in the same sunny, warm conditions as tomatoes, making them easy to grow together without conflict. To maximize the benefits, plant basil near the base of your tomato plants, keeping enough space to allow airflow. Frequent harvesting of basil leaves not only provides a fresh culinary supply but also encourages the plant to grow more vigorously, further contributing to a healthy tomato patch.

Marigolds – The Pest Patrol

Marigolds are more than just cheerful bursts of orange and yellow—they’re natural bodyguards for tomatoes. Their pungent scent deters a range of destructive insects, including nematodes, which attack tomato roots. Certain marigold varieties, particularly French marigolds, are especially effective at repelling whiteflies and aphids. Planting marigolds around the perimeter of a tomato bed creates a natural barrier, helping to protect your crop without the need for harsh chemical pesticides. Beyond their pest-repelling abilities, marigolds attract beneficial insects like ladybugs and hoverflies that prey on harmful pests. This colorful, low-maintenance flower also contributes to soil health, making it an invaluable ally in a companion planting strategy.

Garlic – The Underground Protector

Garlic offers a powerful defense system for tomato plants, working primarily beneath the soil. Its strong aroma confuses and deters pests like spider mites and aphids. Additionally, garlic releases sulfur into the soil, which has natural antifungal properties that can help prevent common tomato diseases such as early blight and powdery mildew. Planting garlic cloves near tomatoes in early spring allows them to establish strong roots while the tomato plants grow taller. This underground partnership not only safeguards tomatoes but also yields a flavorful garlic harvest later in the season. Just be sure to give each plant adequate spacing to prevent overcrowding, as both tomatoes and garlic prefer good airflow around their foliage.

Carrots – Root-Level Cooperation

Carrots and tomatoes share a quiet but beneficial relationship below the surface. While carrots do not directly improve tomato flavor or pest resistance, their fine, narrow roots help break up and aerate the soil around tomato plants. This can improve drainage and root development for tomatoes. In return, the taller tomato plants provide partial shade for the carrots, which can prevent them from bolting too early in hot weather. The key to this partnership is careful spacing—planting carrots too close can make harvesting difficult, but interplanting in wide rows ensures both crops have the room they need to thrive. This pairing allows gardeners to maximize space efficiency without sacrificing quality.

Onions – Aromatic Defense Line

Onions make excellent companions for tomatoes because they repel insect pests such as aphids, thrips, and beetles with their potent scent. Like garlic, onions also help reduce fungal threats in the garden. Their compact growth habit means they can be tucked neatly around tomato plants without competing for sunlight. Onions also mature earlier than tomatoes, so they can be harvested mid-season to free up space for other crops while the tomatoes continue to grow. This staggered harvesting schedule makes onions a smart choice for succession planting alongside tomatoes.

Lettuce – A Cooling Ground Cover

Lettuce may seem like an unlikely tomato companion, but it offers valuable benefits as a living mulch. When planted around tomato bases, lettuce shades the soil, keeping it cooler and reducing moisture loss. This ground cover helps maintain consistent soil moisture levels, which is important for preventing problems like blossom end rot in tomatoes. Lettuce also suppresses weeds, which compete for water and nutrients. Since lettuce grows quickly and prefers cooler conditions, it’s best to plant it early in the season alongside young tomato plants. As the tomatoes grow taller and provide more shade, lettuce continues to flourish until summer heat eventually encourages it to bolt, at which point it can be replaced with another quick-growing ground crop.

Borage – The Bee Magnet

Borage is a lesser-known but highly effective companion plant for tomatoes. Its star-shaped blue flowers are not only beautiful but also rich in nectar, attracting pollinators like bees that help improve tomato fruit set. Borage is also known to repel tomato hornworms, one of the most destructive tomato pests. Additionally, it enriches the soil with trace minerals that can benefit tomato plants over time. Gardeners often find that borage improves the overall resilience of their garden ecosystem, making it a worthwhile addition to any tomato bed. Because borage grows quickly and can become large, it’s best to plant it a short distance from tomatoes rather than directly at their base to prevent shading.

Celery – Moisture-Friendly Companion

Celery is a surprisingly good partner for tomatoes, especially in gardens where maintaining soil moisture is a challenge. Celery thrives in the same consistently moist conditions that tomatoes appreciate, and it doesn’t compete heavily for nutrients. Its upright growth habit allows it to fit neatly between tomato plants without taking up too much space. Celery also contributes to biodiversity in the garden, which can reduce pest outbreaks by attracting a variety of beneficial insects. While celery is slower to mature than many other companions, the combination of visual appeal, culinary use, and garden benefits make it a worthy addition to the tomato patch.

Nasturtiums – The Trap Crop

Nasturtiums are a vibrant and strategic addition to any tomato garden. These edible flowers act as a “trap crop,” luring aphids, whiteflies, and other pests away from tomato plants. Once pests are concentrated on the nasturtiums, gardeners can easily remove the affected plants or treat them without risking damage to the tomatoes. Nasturtiums also repel squash bugs and cucumber beetles, adding extra value for gardeners who grow multiple crops. Their sprawling habit makes them ideal for planting at the base of tomato plants where they can trail along the ground, providing both pest control and weed suppression.

Asparagus – Seasonal Timing Advantage

Asparagus and tomatoes make excellent long-term garden partners because their growing seasons complement each other. In spring, asparagus emerges early and is harvested before tomato plants mature. Once tomatoes begin their rapid summer growth, they help shade the asparagus bed, reducing weed competition and conserving soil moisture. Tomatoes also repel asparagus beetles, while asparagus is believed to deter nematodes that can harm tomato roots. This mutual protection allows both crops to thrive year after year in the same space, making them an efficient choice for perennial planting systems.

Building a Thriving Tomato Ecosystem

The best companion plants for tomatoes create a garden environment where each plant contributes to the success of the others. Whether it’s basil enhancing flavor, marigolds defending against pests, or borage attracting essential pollinators, each companion plays a unique role in supporting healthy tomato growth. By incorporating a diverse mix of herbs, flowers, and vegetables around your tomato plants, you can boost productivity, reduce pest problems, and even improve the taste of your harvest. Successful companion planting is as much about observation as it is about tradition—experiment with different combinations, pay attention to how your plants respond, and adjust your garden plan each season. With thoughtful pairing, your tomato patch can become more than just a row of plants—it can be a dynamic, resilient ecosystem bursting with life, color, and flavor.