Why Runner Beans Don’t Grow (and How to Fix It)

Runner beans should be one of the most generous crops in the garden, climbing to the top of their canes and producing handfuls of pods every few days. So it's disappointing when they sit at the bottom of their supports without growing, or cover themselves in red flowers but give you hardly any beans. Most problems come down to warmth, water or picking, and nearly all can be put right.

Quick answer

Runner beans usually fail to grow because they were sown or planted out while the soil was still cold. They fail to crop because of dry soil at flowering time, poor pollination, or pods left on the plant too long. Wait until the soil has warmed up in late May or June, prepare the ground with plenty of compost, water generously once flowers appear, and pick every two or three days.

What's going wrong?

  • Seeds didn't come up: see "Cold, wet soil".

  • Plants are small and pale and haven't climbed: see "Planted out too early" and "Hungry soil".

  • Plenty of flowers, but few or no beans: see "Flowers falling off without making pods".

  • Plants stopped producing mid-season: see "Pods left to grow too big".

  • Leaves eaten or seedlings vanished: see "Slugs and snails".

  • Black insects on the shoot tips: see "Blackfly".

Cold, wet soil

Runner bean seeds need warm soil to germinate. Sown into cold, damp ground, they often rot before they sprout. According to the RHS, the soil needs to be at around 12°C, with frosts finished. Southern gardens usually get there around the middle of May, while northern ones may have to wait until June.

Fix it: be patient with outdoor sowings. For a head start, sow indoors in pots from mid-April to May, one bean per pot, and plant out once the weather has warmed. See when to plant runner beans in the UK

Planted out too early

Runner beans are tender. A cold night, a frost or a chilly wind can stop young plants in their tracks. They may turn pale or yellow and stop growing for weeks.

Fix it: get indoor-raised plants used to outdoor life gradually by standing them outside during the day for one to two weeks. Hold off planting until the end of May or into June. A layer of fleece on chilly nights gives extra protection. Plants that have stalled usually pick up once the weather warms.

Hungry soil

Runner beans are big, hungry plants, and they need rich, moist soil to climb all the way up 2.5 m canes. In thin, dry soil, they stay small and crop poorly.

Fix it: a few weeks before planting, dig in plenty of rotted manure or homemade compost. The RHS recommends two buckets or more for every square metre. Once the beans are in, a thick layer of compost over the soil stops it drying out. Our guide to the best soil for vegetable gardening in the UK explains how to improve it.

Plants won't climb

Young bean plants sometimes flop around the base of their supports instead of climbing, particularly in windy spots.

Fix it: gently wind the young shoots around the canes and tie them in loosely to get them started. Runner beans twist anticlockwise as they climb (when viewed from above), so wind them the same way or they'll unwind. Make sure the supports are tall and sturdy, about 2.5 m, and firmly pushed into the ground.

Flowers falling off without making pods

This is the most common runner bean complaint. The plant looks lush and flowers well, but the flowers drop and few pods form. The RHS notes it happens most in the first part of the season. The usual causes are:

  • Dry soil: the biggest single cause. Plants short of water at the roots drop their flowers.

  • Hot, dry weather: high temperatures, especially with dry air, make it harder for flowers to form pods.

  • Few pollinators: runner bean flowers need bees to pollinate them. In cool or windy weather, or in gardens with few bees, many flowers go unpollinated.

  • Early flowers: the first flowers often drop before the plant is ready, and later ones usually do better.

Fix it: as soon as the first red flowers open, water more, giving the row a long, slow soak rather than a quick sprinkle. Mulch to hold the moisture in. Grow bee-friendly flowers nearby, such as sweet peas, borage or marigolds. Next year, try a self-fertile variety such as 'Stardust' or 'Firelight', which forms pods more reliably without relying on bees. See how often to water runner beans

Pods left to grow too big

Once a plant has pods full of mature seeds, it stops producing flowers. Leaving even a few big, tough pods on the plant can bring cropping to a halt.

Fix it: pick pods when they're young and tender, about 20–25 cm long, and check every two or three days in summer. Remove any pods that have grown big and lumpy, even if you don't want to eat them. See when to harvest runner beans

Too much shade

Runner beans need plenty of sun to flower and crop well. Grown in shade, the plants get long and thin and produce few flowers.

Fix it: next year, grow them in the sunniest spot you have, with rows running north to south if possible so both sides get sun.

Slugs and snails

Slugs and snails love young runner bean plants and can eat through seedlings overnight.

Fix it: young beans are most at risk in their first few weeks outside, so keep a close eye on them, especially after rain. Check with a torch on a mild, wet night to see how many slugs are about. Plants grown on in pots and planted out at a decent size cope with damage far better. See slugs eating vegetable plants

Blackfly

Clusters of small black aphids on the shoot tips and flower stems weaken plants and can reduce the crop.

Fix it: squash the first few clusters between finger and thumb, or wash them off with the hose. Check the shoot tips every few days, as numbers build up quickly in warm weather.

Diseases

  • Halo blight: small, dark, water-soaked spots on leaves, often with a pale yellow halo. Remove affected leaves or plants, and don't save seed from them.

  • Rust: small orange or brown spots on leaves late in the season. It usually does little harm this late on.

Runner beans in containers

A pot dries out far faster than a bed, and runner beans in containers are the first to drop their flowers in a dry spell. Choose a big, deep tub and water daily once the weather is warm. From the first flowers, feed every fortnight with tomato feed. See growing runner beans in containers

Everything from sowing to picking is covered in how to grow runner beans in the UK. If another crop is struggling, start with why vegetables aren't growing

Common questions

Why are my runner beans flowering but not producing beans?
Usually because the soil is too dry at flowering time, the weather is very hot, or there aren't enough bees about. Water generously once flowers appear, mulch the soil and try a self-fertile variety next year.

Why are my runner beans not growing?
Most often they were sown or planted out while the soil was still cold, or the soil is poor and dry. Wait until late May or June, prepare the ground with plenty of compost and protect young plants from slugs.

Why have my runner beans stopped producing?
Pods left to mature on the plant tell it to stop flowering. Pick every two or three days while the pods are young, and remove any that have become big and tough.

How do I get more beans from my runner beans?
Water deeply once they flower, mulch the soil, pick often and grow them in full sun. Self-fertile varieties such as 'Stardust' and 'Firelight' form pods more reliably.

Sowing temperatures, soil preparation and varieties based on RHS guidance.

 
laura tennant