When to Plant Runner Beans

Why grow runner beans?

Runner beans are one of the most rewarding crops for UK gardens. They grow fast, produce generously, and look great climbing up supports with their bright flowers and lush green foliage. Perfect for small gardens or allotments, they can be trained upwards, saving ground space while delivering plenty of pods.

When should you plant runner beans

Runner beans are sensitive to frost, so timing is key. Sow indoors from mid-April in pots or trays to get a head start. Outdoors, wait until all risk of frost has passed—usually late May to early June, depending on your region. Cold soil will stall germination, so don’t rush it. Warmer, settled weather helps seedlings get off to a strong start.

Choosing the right variety

There are many varieties of runner bean, including traditional tall growers like ‘Scarlet Emperor’ and dwarf types such as ‘Hestia’ for containers. Most have red or bi-coloured flowers and long green pods, but some offer stringless or coloured options. Choose a variety that suits your growing space and taste preference.

How to sow runner bean seeds

For indoor sowing, fill 9cm pots with multipurpose compost and push a single seed 5cm deep into each one. Keep them in a warm, bright spot and water lightly. Germination usually takes about a week. For outdoor sowing, sow two seeds at each support, 5cm deep, and thin out the weaker one after they sprout. Spacing is crucial—leave about 20cm between each plant to give them room to climb and breathe.

Preparing the soil

Runner beans need rich, well-drained soil with good moisture retention. Dig over the site in early spring and add plenty of compost or well-rotted manure. Beans are deep-rooted, so it’s worth creating a trench and filling it with kitchen compost or shredded newspaper before backfilling—this helps retain moisture during hot spells.

Supporting runner beans

These are climbing plants and need strong support. Use bamboo canes, wigwams, or a bean frame, making sure it’s tall and sturdy—ideally up to 2 metres high. Put supports in place before planting to avoid disturbing the roots later. Tie in young plants as they start to grow and they’ll soon wind their way upwards on their own.

Planting out runner beans

Once all frost risk has passed and your plants are around 15cm tall, harden them off gradually by placing them outside during the day for a week. Then plant them out, one per cane. Water in well and keep the soil moist during dry spells. Mulching around the base can help retain moisture and reduce weed competition.

How to care for runner beans

Keep the plants watered, especially during flowering and pod formation. Dry roots can lead to poor pollination and fewer beans. Feed every two weeks with a high-potash fertiliser once flowering starts. Regularly pick the beans to keep the plants productive. Leave pods too long and they become stringy and reduce the number of new ones forming.

Boosting pollination

Runner beans rely on pollinators like bees to set pods. In cool or damp weather, flowers may drop without forming beans. Encourage bees by planting companion flowers nearby, and avoid using pesticides during flowering. Some gardeners hand-pollinate by brushing flowers gently to help transfer pollen.

Harvesting runner beans

Pick beans when they’re young, around 15–20cm long and still tender. If you leave them too long, they become tough and fibrous. Regular picking encourages more pods to grow. Harvest every few days during peak season, usually from July to September, depending on when you planted.

Common issues when planting runner beans

Late frosts can kill young plants, and slugs love tender seedlings. Use fleece for early protection and keep an eye out for pests. If flowers drop without forming pods, it’s often due to lack of water or poor pollination. Beans growing in poor soil or exposed to strong wind may also struggle to thrive.