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Introduction

Tomatoes are the stars of the summer garden, but they don’t like to grow alone. Companion planting is one of the easiest and most natural ways to boost tomato growth, improve flavor, and keep pests away—all without relying on chemicals.

I’ve tested many companion plants in my Zone 9 garden, and I can tell you—pairing tomatoes with the right neighbors makes a big difference! Some plants repel harmful bugs, others attract pollinators, and a few even improve tomato health by enhancing soil nutrients.

If you want bigger, healthier tomatoes with fewer problems, keep reading—I’ll show you the best companion plants for tomatoes and which ones to avoid!

Why Companion Planting Works for Tomatoes

Companion planting isn’t just an old gardener’s trick—it’s based on science and plant interactions. The right plant combinations can:

Repel pests naturally, reducing the need for pesticides
Attract pollinators to boost fruit production
Enhance soil nutrients, improving tomato health
Provide shade & support for better growth
Deter fungal diseases by improving airflow

The Best Companion Plants for Tomatoes

These plants will help tomatoes thrive while keeping your garden healthy and pest-free.

1. Basil – The Ultimate Tomato Companion

Basil and tomatoes aren’t just a great pair in the kitchen—they’re perfect partners in the garden, too! Basil improves tomato flavor and repels aphids, whiteflies, and hornworms.

How to Plant:
Space basil 12-18 inches from tomatoes
Pinch back flowers to keep the plant productive
Harvest leaves frequently for best results

Bonus: Basil attracts pollinators like bees, helping increase tomato production!

2. Marigolds – The Natural Pest Fighter

Marigolds are one of the best natural pest repellents for tomatoes. They release a compound that deters nematodes, whiteflies, and aphids.

How to Plant:
Place marigolds around the base of tomato plants
Use French marigolds for best nematode control
Deadhead flowers to keep them blooming all season

Pro Tip: Marigolds attract pollinators and beneficial insects like ladybugs, which eat aphids!

3. Onions & Chives – Protect Against Fungal Diseases

Onions and chives naturally repel aphids and mites while also improving tomato health by reducing fungal issues like powdery mildew.

How to Plant:
Space onions or chives 6-8 inches away from tomato plants
Harvest chives frequently to encourage growth
Use chopped chive leaves as natural mulch for tomatoes

Bonus: Chives enhance tomato flavor when grown nearby!

4. Nasturtiums – The Ultimate Trap Crop

Nasturtiums are known as trap crops, meaning they attract pests away from tomatoes. Aphids and whiteflies prefer nasturtiums over tomatoes, keeping your crops safer.

How to Plant:
Grow nasturtiums at the edge of your tomato bed
Choose trailing varieties for best coverage
Let them sprawl to create a living mulch that retains soil moisture

Bonus: Nasturtium flowers are edible and make beautiful garnishes!

5. Carrots – Improve Soil & Save Space

Carrots and tomatoes work well together because carrots help aerate the soil, making it easier for tomato roots to grow.

How to Plant:
Direct sow carrots under tomato plants for natural mulch
Thin them out once they grow to prevent competition
Keep soil moist to encourage deep root growth

Pro Tip: Choose smaller carrot varieties like ‘Parisian’ if planting in containers with tomatoes!

6. Peppers – A Perfect Companion for Small Gardens

Tomatoes and peppers belong to the same family (nightshades) and grow well together. They thrive in similar conditions and don’t compete for nutrients.

How to Plant:
Space peppers and tomatoes 12-18 inches apart
Provide good airflow to prevent fungal disease
Mulch well to retain moisture

Zone 9 Tip: Peppers and tomatoes can grow year-round in warm climates, making them perfect long-term companions!

7. Lettuce – Provides Natural Shade

Lettuce grows quickly and provides living mulch for tomatoes, reducing weeds and keeping the soil cool.

How to Plant:
Tuck lettuce between tomato plants
Harvest frequently to prevent overcrowding
Water lettuce well—it thrives in moist soil

Bonus: Lettuce helps retain moisture for tomatoes in hot summer months!

What NOT to Plant Near Tomatoes

Some plants don’t play well with tomatoes. Avoid these bad companions to prevent stunted growth, disease, or pest issues.

Plant	Why to Avoid It
Cabbage & Broccoli	Competes for nutrients, stunts tomato growth
Corn	Attracts tomato hornworms
Fennel	Releases chemicals that inhibit tomato growth
Potatoes	Attracts blight, which can spread to tomatoes

Pro Tip: If space is limited, plant these far away from your tomato bed!

Companion Planting Chart for Tomatoes

Best Companion Plants	Benefits
Basil	Repels aphids, enhances flavor
Marigolds	Repels nematodes & whiteflies
Onions & Chives	Prevent fungal diseases
Nasturtiums	Attracts aphids away from tomatoes
Carrots	Loosens soil for tomato roots
Peppers	Thrives in the same conditions
Lettuce	Provides shade & prevents weeds

Final Thoughts

Companion planting is an easy, natural way to grow healthier tomatoes while improving soil health, reducing pests, and increasing your harvest. Whether you add basil for better flavor, marigolds for pest control, or lettuce for moisture retention, your tomato plants will thank you with bigger, juicier fruit.

Want more tomato-growing tips? Check out:

• How to Transplant Tomatoes for Maximum Growth
• Organic Fertilizer Basics
• How to Grow Tomatoes in Zone 9

What companion plants have worked best for your tomatoes? Let me know in the comments!