How to grow runner beans / RHS Gardening

Sow

Runner beans are tender plants that won’t survive frost, so for an early crop sow indoors in late spring. You can also sow outdoors in early summer.

Sow indoors

If you have room, start runner beans off indoors on a windowsill or in a propagator, in late April or May. Sow one bean per small pot, 5cm (2in) deep.

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Harden off young plants, to acclimatise them to outdoor conditions, but wait to plant them out until all risk of frost has passed, usually in late May/early June.

Sow outdoors

You can sow outdoors in late May or June, after the last frost. It’s best to sow in pots – one bean per small pot, 5cm (2in) deep. Place the pots in a coldframe or sheltered position.

Once the plants reach 8cm (3in) tall, plant them into their final positions. This will be in June or July.

Alternatively, sow directly in the ground from mid-May to late June. Sow two seeds at the base of each cane (see below), 5cm (2in) deep and spaced 15cm (6in) apart. Thin to one seedling per cane, and protect plants from slugs and snails. For the ideal site, see below.

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Grow

How to grow runner beans / RHS Gardening

Runner beans need a warm, sunny spot in well-drained soil. Before you sow or plant out your beans, fork in lots of well-rotted manure or garden compost.

Runner beans need a support to climb up. The traditional method is to grow them up inward-sloping 2.4m (8ft) tall bamboo canes tied near their tops to a horizontal cane, like an A frame. However if you slope the bamboo canes so they meet in the middle and tie them there, with the ends of the canes extending beyond the row (more like an X), picking is easier and the yield is usually better.

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In smaller spaces, a wigwam of canes takes up less room and creates an ornamental feature.

Loosely tie the plants to their supports after planting; after that they will climb naturally. Remove the growing point once the plants reach the top of their support. This encourages side stems.

Flower set

Runner beans sometimes fail to ‘set’, or produce pods, after flowering, and there are a number of causes and solutions.

  • Ensure the soil is constantly moist and doesn’t dry out. Add mulch after planting and water regularly and generously, ideally in the evenings.

  • Flower set is better in alkaline, chalky soils. If your soil is neutral or acidic, try applying lime.

  • If this is a recurring problem and you live in a mild area, try growing beans with some French bean parentage, which set pods more easily in warmer summers. Examples include ‘Firestorm’ and ‘Moonlight’.

More on problems with runner bean flower set

Common problems

Black bean aphid
How to grow runner beans / RHS Gardening

Sap-sucking aphids will disfigure plants and cause stunting to leaves and stems.

Remedy

In the case of broad beans, pinch out infested tips. On other beans, catch populations when small and squash.

Slugs and snails
How to grow runner beans / RHS Gardening

These feed on the young seedlings and you’ll see the tell tale slime trail on the soil around your crop, as well as on the leaves.

Remedy

There are many ways to control slugs and snails, including beer traps, sawdust or eggshell barriers, copper tape and biocontrols.

No/ very few beans
How to grow runner beans / RHS Gardening

This is one of the most common problems of bean growing and is usually caused by lack of moisture and/or poor pollination by insects.

Remedy

Plant or sow beans into soil that has had plenty of organic matter, such as well-rotted manure added the previous autumn, as this will aid moisture and nutrient retention around the roots. Plant in a sheltered site as this will encourage bees to visit and pollinate the plants.

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Harvesting

Cropping starts around mid-summer, depending on the variety and when the seeds were sown, and continues for eight weeks or more if harvested regularly.

It’s best to pick pods when young and tender, about 15–20cm (6–8in) long, and certainly before the beans inside begin to swell.

Regular harvesting is essential, to prevent any pods reaching maturity. Once this happens, plants will stop flowering and no more pods will form. 

Recipes

Nigel Slater recommends serving runner beans with lemon and garlic crumbs, as a lovely side dish for grilled fish.

Recommended Varieties

‘Benchmaster’ AGM

Good  crops of long, smooth, tender beans in clusters with exhibition potential if grown well. Frost tender, plant out after last frosts. Needs strong supports to climb up. High in vitamin C, foliate and iron with good fibre content.

‘Enorma – Elite’ AGM

Fine textured beans, capable of winning local shows. Plants can grow up to 3 metres high. Pick young for continuity of cropping and freezing.

‘Firelight’ AGM

Virtually self-fertile scarlet flowered beans with improved pod-set even in hot dry summers. British bred.

‘Moonlight’ AGM

Major breakthrough in runner bean breeding, crossed with french bean to give early cropping, self-fertile, stringless beans, cropping well in less than ideal conditions. White flowered.

‘Stardust’ AGM

Another runner/French bean hybrid, British bred, self-fertile, white flowered, high cropping variety, whatever the weather. Freezes well.

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