The best companion plants for tomatoes

By Sophie Sparkes · Updated September 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.

Short answer: if you only plant three things alongside tomatoes, make them basil, French marigolds and nasturtiums. Keep potatoes, brassicas, fennel and walnut trees well away.

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.

Tomato companion planting questions

What can I plant with tomatoes in a pot or container?

Basil and chives are the best container companions: both stay small, neither competes hard for food, and both earn their place in the kitchen. A few cut-and-come-again salad leaves will fill the surface early in the season. Avoid pairing a tomato with another hungry crop in the same pot, and go bigger than feels necessary, because a tomato in a cramped container dries out and stalls.

What can I plant with tomatoes to keep bugs away?

French marigolds are the workhorse: their scent deters whitefly and aphids, and their roots suppress root-knot nematodes in the soil. Nasturtiums work differently, as a trap crop that aphids and blackfly go to instead of your tomatoes. Onions, chives and garlic add a third layer, because the allium scent confuses pests looking for tomato plants.

Can I plant tomatoes and peppers together?

Yes. They are close relatives and want the same things: sun, warmth, rich soil and steady water, so they are easy to grow side by side. The catch is that being related means they share pests and diseases, so give them enough space for air to move between the plants rather than packing them tight.

Can I plant tomatoes and cucumbers together?

Yes, and it is a common greenhouse pairing, but they are not a perfect match. Cucumbers want more humidity and more water than tomatoes do, so you end up compromising on both. If you have the room, grow them in separate beds or at opposite ends of the greenhouse and keep the airflow good.

What should you never plant next to tomatoes?

Potatoes, because they are close relatives that share blight and the same pests. Brassicas such as cabbage, broccoli and kale, because they are heavy feeders that compete for nutrients and can stunt the tomatoes. Fennel, which inhibits the growth of many neighbouring plants. And nothing within the root zone of a walnut tree, which releases juglone, a chemical toxic to tomatoes.