Best Companion Plants for a Productive Vegetable Patch

Why Companion Planting Earns Its Space

Allotments and kitchen gardens are usually short of room. Every square foot has to justify itself, which is why companion planting appeals: you plant something that does a job as well as looking good. Some companions mask the scent of a crop so pests struggle to find it, others act as a decoy and draw attackers away, and a few simply fill gaps with flowers that bring in bees and hoverflies at exactly the moment your beans and courgettes need pollinating.

None of it replaces good cultivation. Healthy soil, sensible rotation, mulching and watering still do most of the heavy lifting. But used thoughtfully, companion groupings make a small plot work harder, and they make the whole business of growing vegetables far more pleasant to look at.

Marigolds: Small Flowers, Big Returns

The tagetes family is the first thing I suggest to anyone starting a veg patch. French marigolds (Tagetes patula) are compact, cheap from seed, and flower from June until the first frost, usually well into October in a sheltered spot. Scatter them along the front of a raised bed or dot them between brassicas and you get a season of colour plus a genuinely useful deterrent.

Their roots release compounds that suppress certain soil-borne eelworms, which is why they are traditionally grown before or alongside tomatoes and potatoes. Above ground, the strong, slightly resinous scent confuses whitefly and aphids, and the open flowers are a magnet for hoverflies whose larvae eat greenfly by the dozen.

Pot marigolds (Calendula officinalis) are a different plant entirely and equally worthwhile. Hardy, tolerant of poor soil, and happy to self-seed, they draw in bees early in the year and the petals are edible. Sow a short row near courgettes or runner beans and let them get on with it.

Nasturtiums: The Sacrificial Trap Crop

Nasturtiums are the classic decoy. Blackfly adore them, and given the choice they will colonise the nasturtium before your broad beans or cabbages. That is the point: you inspect the decoy, squash the colonies, and your crop stays clean. Grow a clump at each corner of the brassica bed, and another near the beans.

• Choose compact varieties for beds and the climbing sort for wigwams and fences.
• Sow direct in May, three or four seeds per station, in poor soil — rich ground gives leaves at the expense of flowers.
• Check them every few days and remove aphid-heavy leaves rather than letting numbers build.
• Young leaves and flowers are peppery and excellent in a salad, so nothing is wasted.

One caution: nasturtiums self-seed with enthusiasm. Pull seedlings where you do not want them in early spring, or you will be dealing with them for years.

Basil and Other Aromatic Allies

Basil earns its place beside tomatoes for reasons of flavour, but it also repels whitefly and thrips and is said to improve growth. Grow it in pots sunk between tomato plants, or in a row along the south side of the greenhouse bed. Keep pinching out the tips to stop it running to flower, and sow a second batch in July to keep the supply going.

Other aromatics do similar work in different parts of the plot. Chives and garlic chives planted among carrots mask the scent that carrot root fly follows, and their purple pom-pom flowers feed bees. Dill attracts predatory wasps that hunt caterpillars, so let a few plants bolt near the brassicas. Rosemary, sage and thyme make a fragrant, drought-tolerant hedge around a bed and confuse a range of flying pests. Mint works well too, but keep it in a pot sunk into the ground unless you want a mint takeover.

Groupings That Work in a Small Plot

The trick with limited space is to interplant rather than set aside separate beds for flowers. A few combinations that have served me well:

• Tomatoes, basil and French marigolds in the same bed or greenhouse border.
• Carrots, chives and spring onions sown in alternating rows — the onion scent covers the carrot.
• Brassicas with nasturtiums, dill and rosemary, with the decoy clumps at the edges where cabbage white butterflies arrive first.
• Sweetcorn, climbing beans and courgettes together — the beans fix nitrogen, the corn gives the beans something to climb, and the courgettes sprawl over the soil as a living mulch.
• Strawberries with borage, which brings in pollinators and looks lovely sprawling between the plants.

Productive Rules of Thumb

A few practical points stop companion planting becoming a muddle. Keep tall, vigorous companions away from low growers that need light — dill and fennel cast shade and fennel in particular suppresses nearby plants, so give it its own corner. Space everything properly; crowding to squeeze in one more marigold invites mildew. Remember that flowers need water and feeding too, or they will sulk and stop producing nectar just when pollinators need them.

Finally, treat companion planting as one thread in a bigger tapestry. Rotate your crops, feed the soil with homemade compost each autumn, and leave a few seedheads standing over winter for the birds. Do that, and the flowers you slip between the rows will simply be the finishing touch on a patch that is already doing well.