What is Companion Planting?
Companion planting is the practice of growing different plants in close proximity so they can benefit one another. It's one of the oldest and most effective techniques in the gardener's toolkit — and it costs nothing extra if you're already planning your beds. The right plant partnerships can deter pests, attract beneficial insects, improve soil health, and even enhance the flavour of your crops.
In this guide, we cover some of the most tried-and-tested companion planting combinations, all well-suited to UK gardens and growing conditions.
1. Tomatoes & Basil
Perhaps the most famous companion planting duo, tomatoes and basil are a match made in the kitchen and the garden. Basil is believed to repel aphids, whitefly, and tomato hornworm, while many gardeners swear it improves the flavour of tomatoes grown nearby. Basil also attracts pollinators, which helps fruit set on your tomato plants.
How to grow them together: Plant basil around the base of your tomato plants, spacing plants 30cm apart. Both thrive in a warm, sunny spot with well-drained soil.
Shop the pairing:
- Johnsons Tomato Moneymaker Seeds — a reliable, heavy-cropping classic
- Johnsons Tomato Sungold F1 Seeds — sweet cherry tomatoes, perfect for containers
- Johnsons Basil Sweet Seeds — the ideal companion
2. Tomatoes & Marigolds
Marigolds are arguably the hardest-working companion plant in the garden. Their strong scent confuses and deters a wide range of pests including aphids, whitefly, and even nematodes in the soil. Planted around tomatoes, brassicas, or any vegetable bed, they act as a living pest barrier — and they look beautiful doing it.
French and African marigolds (Tagetes) are the most effective varieties for pest deterrence. Pot marigolds (Calendula) are slightly different but still attract beneficial insects like hoverflies and lacewings, whose larvae feast on aphids.
How to grow them together: Interplant marigolds throughout your vegetable beds or use them as a border. Sow from March–May for summer-long protection.
Shop the pairing:
- Johnsons Marigold (African) Double Mix Seeds — bold, pest-deterring blooms
- Johnsons Calendula Pot Marigold Nova Seeds — great for attracting beneficial insects
3. Roses & Garlic
Roses and garlic have been paired together for centuries, and for good reason. Garlic's pungent sulphur compounds are thought to repel aphids, blackfly, and even fungal diseases like black spot — one of the most common rose problems in UK gardens. Some gardeners also report that roses grown near garlic have a stronger fragrance.
How to grow them together: Plant garlic cloves around the base of your rose bushes in autumn or early spring, spacing them 10–15cm apart. They won't compete for nutrients and will die back naturally by midsummer.
Shop the pairing:
- Taylors Bulbs French Garlic Arno Bulbs — excellent flavour and reliable performance
- Taylors Bulbs Garlic Garcua 2 Pack Bulbs — great for planting in multiples around borders
4. Nasturtiums as a Sacrificial Crop
Nasturtiums are one of the most versatile companion plants you can grow. They act as a sacrificial crop — attracting blackfly and aphids away from your prized vegetables and onto themselves instead. This keeps your beans, courgettes, and brassicas cleaner without the need for chemical intervention.
They also attract predatory insects like hoverflies and ladybirds, which will then move on to tackle pests elsewhere in the garden. As a bonus, nasturtium flowers and leaves are edible — peppery and delicious in salads.
How to grow them: Sow direct from April–June in any sunny or partially shaded spot. They thrive in poor soil — too much fertility and you'll get all leaves and no flowers.
Shop nasturtiums:
- Johnsons Nasturtium Jewel Mix Seeds — a vibrant mix of colours, great for borders and veg beds
- Mr Fothergill's Nasturtium Collection Seeds — a curated collection for maximum variety
5. The Three Sisters: Sweetcorn, Beans & Squash
The Three Sisters is a Native American planting system that has stood the test of time for thousands of years — and works brilliantly in UK kitchen gardens too. The three plants support each other in a beautifully balanced way:
- Sweetcorn grows tall and provides a natural climbing frame for beans.
- Climbing beans fix nitrogen from the air into the soil, feeding the other two plants.
- Squash or courgette spreads along the ground, shading out weeds and retaining soil moisture with its large leaves.
Together, they maximise space, reduce weeding, and improve soil fertility — all without a bag of fertiliser in sight.
How to grow them: Start sweetcorn indoors in April, then plant out in a block (not a row — they're wind-pollinated) from late May. Add beans and squash around the base once the corn is established.
What to Avoid: Bad Companions
Just as some plants thrive together, others actively inhibit each other. A few combinations to avoid:
- Onions & beans/peas — alliums stunt the growth of legumes.
- Fennel & most vegetables — fennel is allelopathic and inhibits the growth of many nearby plants. Best grown in its own spot.
- Brassicas & tomatoes — they compete for similar nutrients and can harbour shared pests.
Getting Started
Companion planting doesn't require a complete garden redesign. Start small — tuck a few marigolds between your tomatoes, or sow a row of nasturtiums along your vegetable bed edge. Observe what works in your garden over the season, and build from there.
The best companion planting schemes are ones you'll actually maintain, so keep it simple to begin with and expand as your confidence grows.
Browse our full range of seeds and bulbs to start planning your companion planting combinations this season.