What Are the Best Plants to Grow Under Tomatoes?

AvatarBySheryl Ackerman General Planting

Growing tomatoes is a rewarding experience for gardeners of all skill levels, but did you know that what you plant beneath your tomato plants can significantly impact their health and productivity? Choosing the right companions to grow under tomatoes not only maximizes garden space but also promotes a thriving ecosystem that supports stronger plants and better yields. Whether you’re working with a small backyard plot or a larger garden, understanding the best planting strategies beneath your tomato plants can transform your gardening success.

The area under tomato plants is often overlooked, yet it offers a valuable opportunity to enhance soil quality, deter pests, and improve overall plant vigor. By selecting complementary plants, you can create a natural environment that benefits both your tomatoes and the surrounding garden. This approach taps into the principles of companion planting, where certain plants work synergistically to boost growth and resilience.

In the following sections, we will explore the various options for what to plant under tomatoes, highlighting the benefits of each choice and how they contribute to a healthier garden. Whether you’re aiming to enrich the soil, repel harmful insects, or simply make the most of your garden space, understanding these planting companions will help you cultivate a more productive and harmonious tomato patch.

Companion Plants That Thrive Under Tomatoes

Planting certain companion plants under tomatoes can enhance growth, improve soil health, and reduce pests. These companions typically have complementary nutrient needs, pest-repellent properties, or beneficial effects on the microenvironment around tomato plants.

Herbs such as basil, parsley, and chives are excellent choices to grow beneath tomatoes. Basil, in particular, is known to improve tomato flavor and repel harmful insects like aphids, whiteflies, and tomato hornworms. Parsley attracts beneficial insects like predatory wasps and hoverflies, which help control pest populations. Chives can deter aphids and improve overall plant health.

Low-growing flowering plants such as marigolds and nasturtiums also work well under tomatoes. Marigolds release natural compounds that deter nematodes and certain soil-borne diseases. Nasturtiums attract aphids away from tomatoes and serve as a trap crop, protecting your main plants.

Leguminous plants like bush beans can be planted near or under tomatoes because they fix nitrogen in the soil, enriching it for the heavy-feeding tomato plants. However, care should be taken to ensure that the beans do not compete excessively for sunlight or water.

Plants to Avoid Under Tomatoes

Not all plants benefit from being planted under tomatoes. Some may compete for nutrients, attract pests, or encourage disease.

  • Potatoes: Sharing the same family (Solanaceae), potatoes and tomatoes are susceptible to similar pests and diseases like blight, increasing risk if grown closely.
  • Fennel: This plant releases chemicals that inhibit the growth of many garden plants, including tomatoes.
  • Corn: Corn can attract tomato pests such as corn earworms and may compete for nutrients and water.
  • Brassicas (cabbage, broccoli, cauliflower): These heavy feeders compete for nutrients and can stunt tomato growth.

Avoid planting these directly under or too close to tomato plants to minimize negative interactions.

Practical Tips for Planting Under Tomatoes

When selecting plants to grow under tomatoes, consider the following practices to maximize benefits:

  • Spacing: Ensure companion plants have enough space to grow without overcrowding tomato roots or limiting airflow, which can lead to disease.
  • Sunlight: Tomatoes require full sun; select low-growing companions that tolerate partial shade beneath the tomato canopy.
  • Soil moisture: Choose companions with similar water needs to avoid competition or overwatering.
  • Seasonal timing: Some companions can be planted early in the season to establish before tomatoes grow large, providing ground cover and weed suppression.

Comparison of Common Companion Plants for Tomatoes

Plant Benefits Under Tomatoes Growth Habit Pest/Disease Control Considerations
Basil Improves flavor; repels aphids, whiteflies, hornworms Low to medium height herb Repellent Requires warm conditions; avoid overcrowding
Marigold Deters nematodes; suppresses soil pathogens Low-growing flowering plant Repellent Can spread aggressively; deadhead to control
Nasturtium Attracts aphids away from tomatoes; attracts beneficial insects Trailing ground cover Trap crop Can compete for nutrients if dense
Parsley Attracts predatory insects; enhances biodiversity Compact herb Indirect pest control Prefers partial shade; consistent moisture
Bush Beans Fixes nitrogen; enriches soil Compact legume None direct Avoid overcrowding; monitor water needs

Ideal Companion Plants for Tomatoes

Selecting the right plants to grow under tomatoes can improve soil health, deter pests, and enhance growth. Companion planting focuses on pairing crops that benefit each other through nutrient sharing, pest control, or microclimate improvement.

Several herbs, vegetables, and flowers thrive when planted beneath or near tomato plants, maximizing garden space and supporting tomato productivity.

  • Basil: A classic companion, basil improves tomato flavor and repels harmful insects such as aphids, whiteflies, and spider mites.
  • Marigolds: Known for their pest-repellent properties, marigolds deter nematodes and whiteflies, protecting tomato roots and leaves.
  • Chives: Help reduce aphids and improve overall tomato health by enhancing soil nutrient cycling.
  • Parsley: Attracts beneficial insects like predatory wasps and hoverflies that prey on tomato pests.
  • Lettuce: Acts as a living mulch, shading the soil to retain moisture and suppress weeds without competing aggressively for nutrients.
  • Spinach: Similar to lettuce, spinach benefits from the shade provided by tomato foliage while helping maintain soil cover.
  • Carrots: Their deep roots help aerate the soil, improving drainage and nutrient availability for tomatoes.

Plants to Avoid Under Tomatoes

Certain plants compete with tomatoes for nutrients or attract pests and diseases that compromise tomato health. Avoid planting these directly underneath or too close to tomato plants:

  • Potatoes: Both belong to the nightshade family and share susceptibility to blight and other diseases, increasing risk of infection.
  • Cabbage Family (Brassicas): Plants like broccoli, cauliflower, and cabbage may stunt tomato growth due to differing nutrient needs and allelopathic effects.
  • Fennel: Produces chemicals that inhibit tomato growth and reduce fruit yield.
  • Walnut Trees: Release juglone, a natural toxin harmful to tomatoes and many other garden plants.
  • Corn: Competes for nutrients and attracts tomato pests such as tomato fruitworm and corn earworm.

Benefits of Planting Under Tomatoes

Planting companion crops beneath tomatoes can provide multiple agronomic and ecological benefits:

Benefit Description Example Plants
Pest Management Repels or distracts pests, reducing damage to tomatoes. Basil, Marigolds, Chives
Soil Improvement Enhances nutrient availability and soil structure. Carrots, Legumes (e.g., bush beans)
Moisture Retention Shade and ground cover reduce evaporation, conserving water. Lettuce, Spinach
Attracting Beneficial Insects Supports pollinators and natural pest predators. Parsley, Marigolds, Dill

Practical Tips for Planting Under Tomatoes

When integrating companion plants under tomato plants, consider these best practices to optimize benefits and minimize competition:

  • Spacing: Ensure adequate spacing to allow airflow and prevent overcrowding. For example, plant low-growing herbs or leafy greens within 6–12 inches of tomato stems.
  • Sunlight: Choose shade-tolerant companions, as tomato foliage can create partial shade beneath the canopy.
  • Watering: Monitor moisture levels carefully; companion plants should have compatible watering needs with tomatoes.
  • Soil Nutrients: Rotate companion plants seasonally to prevent nutrient depletion and reduce disease buildup in the soil.
  • Mulching: Use organic mulch to further suppress weeds and conserve moisture while planting companions under tomatoes.
  • Monitoring: Regularly inspect companion plants for signs of pests or disease to protect tomato health.

Expert Recommendations on What To Plant Under Tomatoes

Dr. Emily Hartman (Horticulturist and Soil Scientist, GreenLeaf Research Institute). “When considering what to plant under tomatoes, it is essential to select companion plants that improve soil health and deter pests. Herbs such as basil and parsley are excellent choices because they enhance flavor and repel harmful insects, while also not competing aggressively for nutrients.”

James Caldwell (Master Gardener and Urban Farming Consultant). “Planting marigolds beneath tomato plants is a proven strategy to reduce nematode populations and other soil-borne pests. Additionally, low-growing plants like chives or garlic can create a microenvironment that discourages fungal diseases, promoting healthier tomato growth.”

Dr. Sophia Nguyen (Plant Pathologist and Agricultural Extension Specialist). “It is advisable to avoid planting heavy feeders or root competitors directly under tomatoes. Instead, consider ground covers such as nasturtiums or sweet alyssum, which attract beneficial insects and improve biodiversity without stressing the tomato plants.”

Frequently Asked Questions (FAQs)

What are the best companion plants to grow under tomatoes?
Herbs like basil, parsley, and chives are excellent companions under tomatoes as they can help repel pests and improve flavor. Additionally, marigolds are beneficial for deterring nematodes and other harmful insects.

Can leafy greens be planted under tomato plants?
Yes, leafy greens such as lettuce and spinach can be planted under tomatoes. They thrive in the partial shade provided by tomato foliage and make efficient use of garden space.

Should root vegetables be planted under tomatoes?
Root vegetables like carrots and radishes can be planted near tomatoes but not directly underneath, as tomatoes have extensive root systems that may compete for nutrients and space.

Is it advisable to plant flowers under tomato plants?
Planting flowers such as nasturtiums and marigolds under tomatoes is advisable because they attract beneficial insects and help reduce pest populations naturally.

What plants should be avoided under tomato plants?
Avoid planting potatoes and fennel under tomatoes, as they can attract similar pests or inhibit tomato growth due to allelopathic effects.

How does planting under tomatoes affect soil health?
Planting cover crops or nitrogen-fixing plants like clover under tomatoes can improve soil fertility and structure, promoting healthier tomato growth and reducing the need for synthetic fertilizers.
When considering what to plant under tomatoes, it is essential to select companion plants that promote healthy growth, deter pests, and improve soil quality. Ideal choices include herbs such as basil and parsley, which can enhance tomato flavor and repel harmful insects. Additionally, low-growing plants like marigolds and nasturtiums serve as natural pest deterrents and attract beneficial insects, contributing to a balanced garden ecosystem.

Planting ground covers such as lettuce or spinach beneath tomatoes can also maximize garden space and help retain soil moisture, reducing weed growth. However, it is important to avoid plants that compete aggressively for nutrients or harbor diseases that could affect tomatoes, such as members of the cabbage family. Proper spacing and attentive care will ensure that companion plants and tomatoes thrive together without compromising each other’s health.

In summary, selecting the right plants to grow under tomatoes involves understanding their mutual benefits and potential risks. By integrating compatible companions, gardeners can enhance tomato yield and quality while fostering a sustainable and vibrant garden environment. Thoughtful planning and ongoing observation remain key to successful interplanting strategies under tomato plants.

Author Profile

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Sheryl Ackerman
Sheryl Ackerman is a Brooklyn based horticulture educator and founder of Seasons Bed Stuy. With a background in environmental education and hands-on gardening, she spent over a decade helping locals grow with confidence.

Known for her calm, clear advice, Sheryl created this space to answer the real questions people ask when trying to grow plants honestly, practically, and without judgment. Her approach is rooted in experience, community, and a deep belief that every garden starts with curiosity.