Plants You Should Never Grow Near Tomatoes
Growing tomatoes is one of the most rewarding things you can do in a home garden — but plant the wrong neighbors and you'll sabotage your entire crop before it even sets fruit. Knowing which plants to keep away from tomatoes is just as important as knowing which ones help them thrive.
In this guide, we'll walk you through the plants you should never grow near tomatoes, explain exactly why they cause problems, and show you which beautiful flowers and companion plants actually support a healthy tomato garden. We'll also share some of our favorite premium flower seeds that make excellent tomato companions — adding color, attracting pollinators, and keeping pests at bay.
Why Companion Planting Matters for Tomatoes
Tomatoes are heavy feeders with specific soil, light, and moisture needs. They're also highly susceptible to fungal diseases, certain pests, and allelopathic chemicals — natural compounds released by some plants that inhibit tomato growth. Getting your plant placement right can mean the difference between a bumper crop and a disappointing season.
đźš« Plants You Should Never Grow Near Tomatoes
1. Fennel
Fennel is one of the most notorious bad companions in the vegetable garden. It releases allelopathic chemicals from its roots that stunt the growth of nearly every plant nearby — tomatoes included. Keep fennel in a container or in a completely separate bed, far from your tomato patch.
2. Brassicas (Cabbage, Broccoli, Kale, Cauliflower)
Brassicas and tomatoes compete aggressively for the same soil nutrients, particularly calcium and nitrogen. Planting them together leads to nutrient deficiencies in both crops. They also attract different pest populations that can cross-contaminate. Keep your cauliflower and other brassicas in a dedicated bed away from tomatoes.
3. Corn
Corn and tomatoes share a common enemy: the tomato fruitworm (also known as the corn earworm). Growing them together creates a concentrated habitat for this destructive pest, dramatically increasing infestation risk. They also compete for water and nutrients in similar ways.
4. Potatoes
Tomatoes and potatoes are both members of the Solanaceae (nightshade) family, which means they share the same diseases — most critically, late blight (Phytophthora infestans). Planting them near each other creates a fast-spreading disease corridor. Keep them on opposite ends of your garden.
5. Dill (Mature)
Young dill is actually a decent tomato companion — but once dill matures and goes to flower, it produces compounds that inhibit tomato growth. If you want to grow dill nearby, harvest it young and don't let it bolt near your tomato plants.
6. Eggplant
Like potatoes, eggplant is a nightshade family member and shares the same disease and pest vulnerabilities as tomatoes. Grouping them together concentrates risk. Spread your nightshades across different garden zones.
7. Peppers (With Caution)
Peppers are another nightshade, and while some gardeners grow them near tomatoes without issue, they share disease susceptibility and can compete for resources in tight spaces. If you do grow them together, ensure excellent airflow and soil nutrition. (See our guide on growing Tabasco pepper seeds for tips on keeping peppers healthy.)
8. Walnuts (Black Walnut Trees)
Black walnut trees produce juglone, a powerful allelopathic compound that is toxic to tomatoes. Even planting tomatoes within the root zone of a black walnut — which can extend well beyond the tree's canopy — will cause wilting and death. Never plant tomatoes within 50–80 feet of a black walnut.
9. Apricot Trees
Apricot trees are susceptible to the same fungal diseases as tomatoes, particularly Verticillium wilt. Planting tomatoes near apricot trees increases disease pressure on both plants.
10. Sunflowers (With Caution)
Sunflowers produce allelopathic compounds that can inhibit tomato germination and early growth. Mature sunflowers also attract aphids, which can migrate to tomatoes. If you love sunflowers in your garden, give them their own dedicated space away from the tomato bed.
âś… What to Grow Near Tomatoes Instead
The good news: there are plenty of beautiful, productive plants that love growing near tomatoes. Flowers are especially valuable — they attract pollinators, repel pests, and add stunning color to your vegetable garden. Here are six of our favorites from our premium seed collection:
🌸 6 Flower Seeds That Thrive Near Tomatoes
Zinnia Seeds – Crestar Mix
Zinnias are one of the best tomato companions you can plant. They attract butterflies and beneficial insects that pollinate tomatoes, and they lure aphids away from your crop as a trap plant. Our Zinnia Crestar Mix produces stunning double blooms in a rich range of colors — perfect for cutting and for brightening up the vegetable garden all season long.
Nicotiana Seeds – Starmaker Mix
Nicotiana (flowering tobacco) is a fragrant, pollinator-friendly annual that pairs beautifully with tomatoes. Its sticky stems can trap small insects, acting as a natural pest deterrent. Our Starmaker Mix Nicotiana blooms in a gorgeous range of colors and fills the garden with evening fragrance.
Snapdragon Seeds – Snapstar® Champagne
Snapdragons are cool-season beauties that attract bumblebees — some of the most effective tomato pollinators. Plant them at the edges of your tomato bed in early spring for a pollinator boost before your tomatoes even flower. Our Snapstar® Champagne Snapdragons are a premium cut flower variety with tall, elegant stems.
Lisianthus Seeds – Arena 3 Champagne
Lisianthus adds a touch of elegance to any garden bed and attracts a wide range of pollinators. These long-blooming cut flowers are non-allelopathic and won't interfere with tomato growth. Our Arena 3 Champagne Lisianthus is an F1 hybrid with exceptional vase life and garden performance.
Pentas Seeds – Honey Cluster Red
Pentas are powerhouse pollinator plants that bloom continuously in summer heat — exactly when tomatoes need the most pollination support. Their star-shaped flower clusters attract butterflies and hummingbirds. Our Honey Cluster Red Pentas are vivid, heat-tolerant, and easy to grow from pelleted seed. Read our full Pentas growing guide for tips.
Gerbera Daisy Seeds – Royal Deep Pink Dark Eye
Gerbera daisies are cheerful, long-blooming companions that attract beneficial insects without competing with tomatoes for nutrients. Their bold blooms make a stunning border around vegetable beds. Our Royal Deep Pink Dark Eye Gerbera Daisy is a showstopper with rich, saturated color and a dark contrasting center.
đź›’ Shop Our Tomato-Friendly Flower Seeds
đź“– More Growing Guides You'll Love
- French Marigold Seeds Growing Guide | Compact Garden Marigolds — Marigolds are one of the best tomato companions; learn how to grow them right.
- Pentas Seeds | Complete Guide to Growing Pelleted Pentas Seeds — Attract the pollinators your tomatoes need all season long.
- Growing Tabasco Pepper Seeds: A Complete Guide for Gardeners — If you grow peppers near tomatoes, read this first.
âť“ Frequently Asked Questions
What is the worst plant to grow near tomatoes?
Fennel is widely considered the worst companion for tomatoes. It releases allelopathic chemicals that stunt tomato growth and is incompatible with most garden vegetables. Always grow fennel in isolation.
Can I grow peppers next to tomatoes?
Peppers and tomatoes are both nightshades and share disease vulnerabilities. While some gardeners do grow them together, it's best to keep them separated to reduce disease risk and resource competition. If space is limited, ensure excellent airflow and soil fertility.
Do sunflowers hurt tomatoes?
Sunflowers can inhibit tomato germination and early growth through allelopathic compounds. They also attract aphids. It's best to keep sunflowers in a separate bed or at least several feet away from your tomato plants.
What flowers are safe to plant near tomatoes?
Zinnias, marigolds, nicotiana, pentas, snapdragons, lisianthus, and gerbera daisies are all excellent tomato companions. They attract pollinators, deter pests, and don't compete aggressively with tomatoes for nutrients.
Why can't you plant tomatoes near potatoes?
Tomatoes and potatoes are both in the nightshade family and share the same diseases, especially late blight. Planting them together creates a concentrated disease environment where infections spread rapidly between plants.
Can tomatoes and corn be planted together?
No — tomatoes and corn share the tomato fruitworm/corn earworm pest. Growing them together dramatically increases infestation risk for both crops. Keep them in separate garden zones.
What should I plant between tomato plants?
Basil, marigolds, and low-growing flowers like pentas or zinnias work beautifully between tomato plants. They attract beneficial insects, repel pests, and make efficient use of garden space without competing for resources.
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