Best Companion Flowers for UK Veg Beds

The best companion flowers for vegetables are nasturtiums, calendula, poached egg plant, sweet alyssum, borage and French marigolds. Each does a different job. Some lure pests away, some feed the insects that eat aphids, and some bring in bees.

This guide shows which flower to grow with which crop, and what you can honestly expect. For herb pairings, crop partners and the bigger picture, see the companion planting guide.

How companion flowers help a veg bed

Companion flowers help in three main ways. Knowing which is which helps you choose the right flower for your problem.

• Decoys. A flower that a pest likes more than your crop. Nasturtiums do this for blackfly.
• Food for pest-eaters. Open flowers feed adult hoverflies, lacewings and tiny parasitic wasps. Their young eat aphids and other pests.
• Bee magnets. Flowers like borage and phacelia bring bees to crops that need pollinating, such as courgettes, beans and strawberries.

Flowers aren’t magic pest repellents. A flower that feeds hoverflies won’t stop slugs. Match the flower to the job.

Edging a bed with flowers is the simplest plan. Insects visit the flowers, then move on to hunt aphids among the crops.

Nasturtiums: the blackfly decoy

Nasturtiums are the best decoy plant for a UK veg patch. Blackfly, the black bean aphid, love them. They often gather on the nasturtiums instead of your broad beans, runner beans and courgettes.

Sow nasturtiums direct in late spring, after the last frost, about 2cm deep along the edge of the bed. They flower best in poor soil, as rich soil gives lots of leaf. Nasturtiums can also tempt cabbage white butterflies to lay eggs on them, though that’s less reliable than the blackfly effect.

The trick is to keep an eye on them. Once a nasturtium is crawling with blackfly, pick off the worst shoots and bin them before the aphids move back to your crops. The guide to black bean aphids has more ways to deal with them.

Blackfly crowded onto nasturtium leaves means the decoy is working. Pick off and bin the worst leaves before they spread.

Calendula, poached egg plant and alyssum: hoverfly food

Hoverflies are some of the best friends a veg grower has. The adults feed on nectar and pollen, then lay eggs among aphid colonies. Their larvae eat lots of aphids. To bring them in, grow single, open flowers they can feed from.

• Calendula (pot marigold) flowers from early summer to autumn and self-seeds. The guide to growing calendula covers sowing.
• Poached egg plant (Limnanthes douglasii) has yellow and white flowers in late spring. That’s when the first aphids appear. Sow it in autumn for the earliest flowers.
• Sweet alyssum forms a low carpet of tiny white flowers. It’s great along path edges and between rows of salad.

The guide to hoverflies in the garden explains how to spot the larvae, so you don’t mistake them for pests.

A single, open calendula flower lets hoverflies reach the nectar easily. Their larvae then hunt aphids on nearby crops.

Poached egg plant flowers early, just as the first aphids appear. Bees and hoverflies love it.

French marigolds: best under glass

French marigolds (Tagetes patula) are the classic companion for tomatoes. Many growers plant them in greenhouses and polytunnels, where their strong scent may help keep whitefly away. The effect is modest, so treat it as a bonus.

French marigold roots can also reduce some soil pests called nematodes. That only works when marigolds grow as a dense block for a whole season, so it’s a slow, long-term job.

Choose single-flowered varieties. Big double pompon marigolds look cheerful but hide their nectar from insects. The guide on how to grow marigolds explains the different types.

French marigolds between tomatoes are a polytunnel classic. Their scent is strongest in still, enclosed air.

Borage and phacelia: bring in the bees

Some flowers earn their place by helping pollination rather than fighting pests.

Borage has blue starry flowers that bees visit over and over. It’s a popular partner for strawberries, courgettes and beans. It self-seeds freely, so pull out extra seedlings in spring.

Phacelia has lilac-blue flowers that bees and hoverflies love. It also works as a green manure, covering bare soil between crops. Dig it in before it sets seed, or let some flower for insects. The guide to green manures explains how.

Which flowers go with which vegetables?

Flowers won’t stop cabbage white caterpillars on their own. Keep brassicas under fine netting as well.

When to sow companion flowers

Aim to have flowers open before the first aphids arrive in late spring.

Most of these flowers self-seed, so one packet can keep your plot going for years.

Common mistakes with companion flowers

• Choosing double flowers. Pompon marigolds and frilly doubles hide their nectar. Pick single, open flowers.
• Crowding the crop. Too many flowers between plants steal light and water. Use edges and gaps.
• Ignoring the decoy. A nasturtium full of blackfly needs thinning out, or the aphids spread back.
• Expecting total control. Flowers cut pest numbers, but you’ll still need to net brassicas and squash the odd aphid.
• Believing every old pairing. Some traditional pairings don’t hold up. The guide to companion planting myths separates fact from folklore.

Frequently asked questions

What flowers should I plant with my vegetables?

Nasturtiums, calendula, poached egg plant and French marigolds are the easiest picks. Nasturtiums lure blackfly away from beans. Calendula and poached egg plant feed hoverflies, whose larvae eat aphids. French marigolds suit greenhouse tomatoes. Borage and phacelia bring bees to crops that need pollinating.

Do marigolds really keep pests off vegetables?

French marigolds help a little, mostly in greenhouses. Their strong scent may help keep whitefly off tomatoes under glass. Grown as a dense block for a whole season, they may also reduce some soil pests called nematodes. As a quick fix for aphids outdoors, they do little.

How close should companion flowers be to vegetables?

Close enough for insects to move between them, but not crowding the crop. Edge the bed with flowers, or tuck one in every few plants along a row. Leave each crop enough room for light and water. Low flowers like alyssum can run along path edges.

Which flowers attract hoverflies to a vegetable garden?

Single, open flowers attract hoverflies best. Good choices are poached egg plant, calendula, sweet alyssum, phacelia and single cosmos. Hoverflies have short mouthparts, so they need nectar they can reach easily. Their larvae eat lots of aphids.

Can companion flowers replace pesticides on vegetables?

No, but they can cut pest numbers a lot. Expect fewer aphids, not none. Use flowers alongside squashing, hosing off pests, netting and crop rotation. If a pest really gets out of hand, use an approved product for that crop, following the label.

Do nasturtiums attract aphids?

Yes, and that’s the point. Blackfly love nasturtiums and often gather there instead of on your beans. Check the nasturtiums often and pick off badly covered shoots before the aphids spread back to your crops.

Now you know which flowers earn their place, try the guide to growing nasturtiums for the easiest decoy of all, or find more crops and ideas in the vegetable growing section.