Why Companion Planting Earns Its Place

There is something deeply satisfying about a vegetable patch that hums with life. A bed of tidy rows, by contrast, offers pests a clear run at your crops and gives pollinators very little reason to linger. Thread a few flowers and herbs among your vegetables, though, and the whole plot changes character — it becomes a living community rather than a canteen for slugs and aphids.

This is not a new-fangled idea. Cottage gardeners have long tucked marigolds between their tomatoes and let borage sprawl near the strawberry bed, simply because it worked. The principles are straightforward: some plants repel pests with their scent, some lure pests away from the crops you actually want to eat, some bring in bees and hoverflies, and a few improve the flavour or vigour of their neighbours. Best of all, most of them are cheap, easy to grow from seed, and genuinely lovely to look at.

Marigolds: The Hard-Working All-Rounder

If you plant only one companion this year, make it a marigold. French marigolds are the ones to choose — compact, free-flowering and remarkably useful. Their roots release compounds that suppress certain soil nematodes, while their pungent foliage masks the scent of nearby crops, making it harder for whitefly and aphids to home in on them.

Dotted among tomatoes, peppers and aubergines in the greenhouse or a sunny border, they earn their keep twice over. They also work well alongside brassicas, where their scent helps confuse cabbage white butterflies searching for somewhere to lay. Pinch out the first flowers to encourage bushy growth, then deadhead regularly and they will keep blooming right up to the first frosts. A packet of seed costs pennies and sows enough for several beds.

Nasturtiums: A Sacrificial Crop With Benefits

Nasturtiums are the generous type — they will happily take one for the team. Blackfly and cabbage white caterpillars adore them, and while the pests are busy on the nasturtiums, your beans, brassicas and cucumbers are left largely in peace. Grow a few plants at the edge of the patch, or in pots beside the raised beds, and inspect them every few days; you can squash the colonies by hand and spare your vegetables entirely.

They are edible as well, with peppery leaves and flowers that lift a summer salad beautifully. Trailing varieties look charming spilling over the side of a raised bed, while compact ones suit pots on a sunny patio. Treat them mean — rich soil gives you all leaf and precious few flowers.

Borage: The Pollinator Magnet

Borage is the quiet hero of the fruit and vegetable plot. Its star-shaped blue flowers are irresistible to bees, and the more bees you have working the patch, the better your beans, courgettes and fruit will set. Plant it near strawberries for improved pollination and, by most gardeners' reckoning, tastier and more plentiful fruit. Tomatoes and squash appreciate its company too.

It self-seeds freely, so one sowing can keep you supplied for years, and it tolerates poor, dryish ground that would defeat fussier plants. The young leaves taste faintly of cucumber, and the flowers are lovely frozen into ice cubes for summer drinks. Give it space at the back of a border, as it can grow tall and floppy and benefits from a little shelter from the wind.

Aromatic Herbs: Scent as a Shield

Strongly scented herbs confuse pests that navigate by smell, and many of them double as excellent nectar sources once they flower. Let a few go to bloom rather than cropping them relentlessly.

• Basil — the classic partner for tomatoes, both in the bed and on the plate. Grow it between plants in the greenhouse for the warmth it craves.
• Chives — a ring of chives around carrots is said to deter carrot fly, and the mauve pom-pom flowers bring in bees by the dozen.
• Rosemary, sage and thyme — tough, drought-tolerant woody herbs that edge a bed handsomely and are reputed to put off cabbage white butterflies and slugs.
• Mint — useful against ants and cabbage white, but always sink it in a pot, or it will colonise the entire plot before midsummer.
• Dill — draws in hoverflies whose larvae devour aphids. Let a plant or two flower near your brassicas and cucumbers.

Putting It Together in a British Plot

You do not need to redesign the whole garden. A rough rule of thumb is one flower or herb for every three or four vegetable plants, scattered rather than lined up in a separate border. Leave enough room for air to move between plants, as cramped, damp foliage invites disease in our unreliable summers.

Alongside the stalwarts above, try calendula, sweet alyssum, phacelia and poached egg plant. All are easy from seed, all attract hoverflies and bees, and all will make the patch a far prettier place to spend a June evening. Sow a little every few weeks for a long season of colour. Water in the morning where you can, keep on top of the slugs while seedlings are tender, and let a few plants flower rather than pinching everything back.

Do that, and you will find the plot not only looks better but crops better — with fewer sprays, less fuss and a good deal more birdsong and buzzing to enjoy while you fill your trug.