Companion planting guide
Some crops grow better together. Others are best kept apart. This chart covers all 40 vegetables in our database — what to plant next to each one and what to avoid. Scroll down or jump to a specific crop.
Why companion planting works
Plants interact. Some partnerships have proven benefits:
- Pest confusion — Carrots and onions mask each other's scent from carrot fly and onion fly
- Nitrogen fixing — Beans and peas pull nitrogen from the air and store it in the soil. Plant brassicas where legumes grew last year
- Living mulch — Low-growing lettuce or spinach under taller beans shades the soil, reducing weeds and keeping roots cool
- Physical support — The classic “three sisters”: sweetcorn supports beans, which fix nitrogen for squash, which shades the soil
Jump to a crop
Companion planting chart
Lettuce
Spinach
Carrots
Radishes
Broad beans
Peas
Beetroot
Tomatoes
Flowers that belong on the veg patch
Flowers aren't just decorative on an allotment — they're some of the hardest-working companions you can plant. They attract pollinators, repel pests, and make the whole plot look better.
Marigolds (Tagetes)
The allotment essential. French marigolds repel whitefly from tomatoes and deter aphids. Their roots also release a chemical that discourages root-knot nematodes. Plant them around the edges of beds or between rows of tomatoes, peppers, and brassicas.
Plant with: Tomatoes, peppers, aubergines, beans, courgettes, cucumbers, brassicas
Nasturtiums (Tropaeolum)
Brilliant as a “trap crop” — blackfly and caterpillars prefer nasturtiums to your actual vegetables. Plant them near brassicas to lure cabbage whites away. The leaves and flowers are edible too — peppery in salads.
Plant with: Brassicas, courgettes, beans, cucumbers, squash
Borage
A pollinator magnet with striking blue flowers. Bees can't resist it. Plant near courgettes, squash, and runner beans to boost pollination rates. It also attracts hoverflies, whose larvae eat aphids. Self-seeds generously — you'll only need to plant it once.
Plant with: Courgettes, squash, runner beans, strawberries, tomatoes
Lavender
Attracts pollinators and repels carrot fly, moths, and fleas. Best planted along paths or bed edges where you'll brush past it, releasing the scent. Works well as a semi-permanent border plant.
Plant with: Carrots, brassicas, lettuce. Good as a bed border plant
Calendula (Pot marigold)
Not the same as French marigolds but equally useful. Attracts hoverflies and ladybirds (aphid predators), and acts as a trap crop for aphids. The petals are edible and make a natural food colouring. Easy from seed, self-sows freely.
Plant with: Tomatoes, peppers, asparagus, broad beans
Sweet alyssum
Low-growing (5–10cm) ground cover that attracts parasitic wasps and hoverflies. Excellent sown as a living mulch under taller crops. Flowers all summer with minimal care.
Plant with: Brassicas, potatoes, onions. Use as ground cover between rows
Sunflowers
Tall varieties act as a windbreak and support for climbing beans. They attract pollinators and seed-eating birds that also eat pests. Plant at the back of beds or along north-facing edges where they won't shade other crops.
Plant with: Sweetcorn, runner beans, courgettes, squash
Phacelia
One of the best bee plants you can grow. Purple flowers attract a huge range of pollinators. Also works as a green manure — sow in autumn on empty beds, dig in before spring planting. Fast-growing and unfussy.
Plant with: Any crop. Brilliant as a bed border or green manure
Practical tips
Don't overthink it. Companion planting is a helpful guideline, not a rule book. If you only have one bed and need to grow beans next to onions, do it — they'll still grow.
The most reliable companions are the ones that solve a specific problem: carrots next to onions to confuse pests, lettuce under sweetcorn for shade, marigolds around tomatoes for whitefly.
If you're new to growing, focus on getting things in the ground first. Companion planting is refinement, not a prerequisite.
Common questions
What is companion planting?
Growing certain crops near each other because they benefit from the relationship. Benefits include pest deterrence, improved pollination, better use of space, and nutrient sharing.
What vegetables should not be planted together?
Some common combinations to avoid: potatoes and tomatoes (both nightshades, share blight), onions and beans (onions inhibit bean growth), fennel near most vegetables (inhibits growth), and brassicas near strawberries.
Does companion planting actually work?
Some effects are well-documented — carrots and onions confusing each other's pests, marigolds repelling aphids, nitrogen-fixing by beans. Others are based on generations of gardener observation rather than controlled studies. The low-risk, high-reward nature means it's worth doing.