The best companion plants for tomatoes

Updated June 2026 · 6 min read

Companion planting is the simple idea that some plants grow better together — deterring pests, attracting pollinators, or making better use of space. Tomatoes are one of the best plants to pair up. Here's what to grow alongside them, and the few things to keep your distance from.

The best companions for tomatoes

🌿 Basil

The classic partnership — on the plate and in the bed. Basil is said to repel whitefly and tomato hornworm, and its flowers draw in pollinators. Many gardeners swear it improves the flavour of nearby tomatoes too. Plant it in the gaps between your tomato plants.

🌼 Marigolds

French marigolds are one of the most useful plants in the veg garden. Their scent deters whitefly and aphids, and their roots release a compound that suppresses harmful root-knot nematodes in the soil. A ring of marigolds around your tomatoes is a tried-and-tested combo.

🧡 Nasturtiums

Nasturtiums act as a "trap crop" — aphids and blackfly flock to them instead of your tomatoes, keeping the pests in one place and away from your crop. They're edible, pretty, and easy to grow from seed.

🧅 Onions, chives & garlic

The allium family's strong scent confuses and repels many pests that would otherwise home in on tomatoes. Chives are especially handy — low, neat, and they flower beautifully for the bees.

🥕 Carrots

Carrots grow happily below and between tomatoes, making good use of the space without competing much. As the old gardening book title goes, "carrots love tomatoes."

🥬 Lettuce & leafy greens

Quick, low-growing salad leaves tuck neatly under taller tomato plants and benefit from the light shade in high summer, which stops them bolting so fast. A great way to double up your harvest from one bed.

What NOT to plant near tomatoes

• Potatoes — a close relative, so they share the same diseases (like blight) and pests. Keep them well apart.
• Brassicas (cabbage, broccoli, kale) — heavy feeders that compete with tomatoes for nutrients and can stunt them.
• Fennel — releases substances that inhibit the growth of many nearby plants, tomatoes included. Give it its own corner.
• Walnut trees — produce a chemical (juglone) that's toxic to tomatoes. Don't plant within their root zone.

A simple tomato bed plan

If you're starting from scratch, try this: tomatoes down the middle, basil and chives tucked between them, a border of French marigolds around the edge, and a few nasturtiums trailing at the front as a pest trap. Lettuce fills any gaps early in the season. It looks lovely and works hard.