Runner Bean
Phaseolus coccineus · scarlet runner bean · multiflora bean · butter bean
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🖨 Printable care card (PDF)At a Glance
| Botanical name | Phaseolus coccineus |
|---|---|
| Common name(s) | runner bean, scarlet runner bean, multiflora bean, butter bean |
| Family | Fabaceae |
| Plant type | climber (differs from the common bean (P. vulgaris) in several respects: the cotyledons stay in the ground during germination, and the plant is a perennial vine with tuberous roots (though it is frequently treated as an annual in colder climates)) |
| Height × Spread | 2.5–4 m × 100–150 cm |
| Position | Full sun |
| Soil | Fertile, moisture-retentive soil with plenty of well-rotted compost or manure. |
| Flowering | April–September |
| Toxicity | phytohaemagglutinin |
| Native range | Central America |
Overview
Runner bean (Phaseolus coccineus) is a vigorous climbing annual grown throughout the United Kingdom for its long, fleshy pods and ornamental flowers. A member of the Fabaceae (legume) family, it originates from the highlands of Central America and was introduced to British gardens in the seventeenth century, where it has since become a staple of the productive kitchen garden. Runner beans are notable in the UK for their tolerance of cool, damp summers relative to many other bean species, and their ability to fix atmospheric nitrogen through root nodules in association with Rhizobium bacteria, which benefits crop rotation. They are grown for the immature pods, which are eaten as a vegetable, the fresh shelled beans (often called "flageolets" when dried at the green stage), and, in some culinary traditions, the dried mature seeds. The species is half-hardy and is typically sown in the UK from late April through to early June, once the risk of frost has passed.
Appearance
Runner bean is a twining perennial climber grown as an annual, reaching mature heights of 1.8–3 m or more when supported. Stems are square in cross-section and twine anticlockwise around any suitable support. Leaves are trifoliate, with three broad, ovate to rhombic leaflets, often slightly downy and bright to mid-green.
Two principal flower colour forms are widely grown in the UK: the classic scarlet-flowered type, with bright orange-red pea-like flowers, and the white-flowered type, with pure white blooms borne in long racemes. Bicolour cultivars also exist. Flowering typically begins in late June or early July and continues until the first autumn frosts.
Pods are long, straight or slightly curved, and fleshy. Pod length varies considerably by cultivar, from around 15 cm in dwarf forms to 50 cm or more in exhibition cultivars. Immature pods are green, though purple-podded and bicoloured cultivars are available. Mature seeds are large, kidney-shaped, and typically purple, pink, black, or white, often mottled. The root system is shallow and fibrous, with characteristic nitrogen-fixing nodules.
Growing Conditions
Runner beans perform best in a sheltered, sunny site with fertile, moisture-retentive soil. In the UK, an open south- or west-facing position is ideal, ideally sheltered from strong winds, which can snap the brittle stems of tall climbing cultivars. A deep, humus-rich loam produces the strongest growth; on thin or sandy soils, generous additions of well-rotted manure or garden compost in the autumn or early spring are highly beneficial. Soil pH should ideally be between 6.0 and 7.5, although runner beans tolerate mildly alkaline conditions.
The crop is thirsty and performs poorly in dry soil, particularly once flowering has begun, when moisture stress causes flowers and young pods to abort. Mulching in early summer helps conserve soil moisture and keep roots cool.
In the UK, runner beans are reliably productive in the southern and central regions and into the Midlands. In cooler northern areas and exposed sites, season length is reduced, and cloche protection or growing in a polytunnel can extend cropping. They are not frost-hardy and should not be planted out before the risk of frost has passed in late May or early June.
Planting and Care
Sowing and support. Seeds are sown individually in 9 cm pots of multipurpose compost in late April or early May, kept at about 15–18 °C, and germinated in a greenhouse, cold frame, or sunny windowsill. Alternatively, they can be sown direct outdoors in late May or early June once soil temperatures are reliably above 12 °C. Climbing cultivars need a substantial support: traditional cane structures, often in a double row of 2.4 m canes tied at the top in an A-frame, with a horizontal crossbar, are typical. Wigwams of 2.4 m canes work well in smaller plots. Plant out at the base of supports, spacing plants about 15 cm apart along the row, with 45–60 cm between rows.
Watering. Consistent moisture is critical. Water thoroughly at planting and during dry spells, aiming to keep the root zone damp throughout the growing season. In dry summers, a deep soaking twice a week is more effective than light daily watering. Mulching with compost, straw, or grass clippings reduces evaporation.
Feeding. Although runner beans fix some of their own nitrogen, they respond well to additional potassium and phosphorus for pod production. A fortnightly feed with a high-potash liquid fertiliser, such as one formulated for tomatoes, once flowering begins is beneficial. Avoid high-nitrogen feeds, which encourage leafy growth at the expense of pods.
Pruning and training. Once climbing stems reach the top of the support, pinch out the growing tips to encourage side shoots and prevent the plant from becoming top-heavy. Pinch out the growing tip when stems reach the top of the canes. In late summer, removing any old or yellowing lower foliage improves air circulation.
Propagation. Runner beans are propagated by seed. Saving seed from open-pollinated cultivars is straightforward in the UK: allow a few pods to mature and dry on the plant, then harvest, dry further indoors, and store in a cool, dry place. Note that F1 hybrid cultivars will not come true from saved seed.
Seasonal care. From late June onwards, pick pods regularly — ideally every two to three days — while they are young and tender, around 15–20 cm long. Pods left to mature on the plant suppress further flowering. In October, clear spent plants to the compost heap, leaving nitrogen-rich root nodules in the soil to benefit the following crop. Rotate beds: do not grow runner beans, French beans, or peas on the same ground more than once every three to four years.
Common Problems
Poor pod set. A common UK complaint is flowers failing to set pods. Causes include cold nights in early summer, drought stress, very hot weather (above about 28 °C), and inadequate pollination. Regular watering, mulching, and spraying the flowers with water in the evening on hot days can help.
Blackfly. Black bean aphid (Aphis fabae) is the most frequent pest, clustering on young shoot tips and flower trusses from late May onwards. Pinch out infested tips or spray with insecticidal soap; encourage natural predators such as ladybirds and hoverflies.
Slugs and snails. Particularly damaging to young seedlings, both in pots and at planting out. Standard UK controls (biological control with nematodes, beer traps, hand-picking at dusk, or ferric phosphate pellets) are effective.
Halo blight and bacterial brown spot. Bacterial diseases can cause dark spots surrounded by a yellow halo on leaves and pods. There is no curative treatment; remove and destroy affected plants, avoid working among wet foliage, and buy clean seed from a reputable source.
Chocolate spot (Botrytis fabae). More often a problem on broad beans than runner beans, but can occur in damp seasons, causing brown spots on leaves and stems. Improve air circulation, avoid overcrowding, and clear crop debris in autumn.
Birds. Pigeons in particular can damage young shoots, though they are less of a problem on runner beans than on brassicas. Netting or fleece at the seedling stage is usually sufficient.
Popular Varieties
Several well-established runner bean cultivars are widely available in the UK through seed catalogues and garden centres. The following are real, established varieties commonly offered for UK cultivation:
- 'Scarlet Emperor' — A long-established heritage variety with bright scarlet flowers and long, straight pods of good flavour. Heavy cropping and widely grown across the UK; one of the most popular varieties for decades.
- 'Painted Lady' — A heritage cultivar, dating from the 1850s, with distinctive bicolour scarlet and white flowers and good-quality pods. Often grown for its ornamental value as well as cropping.
- 'White Lady' — A white-flowered variety with pale green pods. Generally considered to have a more delicate, less "beany" flavour than red-flowered types, and flowers set more reliably in very hot weather.
- 'Enorma' — A vigorous climbing cultivar producing exceptionally long pods, popular with exhibitors at UK shows. Requires rich soil and consistent moisture to perform well.
- 'Polestar' — A red-flowered, stringless variety with tender pods at all stages. Suitable for the UK climate and a common choice for kitchen gardens.
- 'Hestia' — A dwarf, bush-type runner bean reaching about 45–60 cm, requiring no support. Useful for exposed sites, small gardens, and container growing; produces bicolour red-and-white flowers.
(Note: cultivar availability varies by year and supplier. UK gardeners are advised to consult current seed catalogues such as those from Suttons, Thompson & Morgan, Mr Fothergill's, and the RHS for the latest ranges.)
Cultivars and Varieties
| Cultivar | Height | Flower | Notes | AGM |
|---|---|---|---|---|
| 'Aeron Purple Star' | — | purple pods | not available commercially | |
| 'Black Runner' | — | — | — | |
| 'Butler' | — | — | — | |
| 'Case Knife' | — | — | — | |
| 'Fasolia gigantes' | — | — | white bean which originated in Greece | |
| 'Hammond's Dwarf' | — | — | — | |
| 'Japanese Runner' | — | — | sold in Canada and USA under the names of 'Akahana' or 'Shinshu runner' | |
| 'Painted Lady' | — | — | — |
Pests and Diseases
| Problem | Symptoms | Management |
|---|---|---|
| Runner and French bean rust | Pale spots on upper leaves develop into brown or black pustules on the undersides, causing leaves to shrivel and die. | Thin out dense growth to improve air circulation and reduce humidity around the foliage. |
| Black bean aphid (blackfly) | Dense colonies of small black insects cluster on stems, leaves, and growing tips, causing distortion and stunted growth. | Encourage natural predators like ladybirds or use a strong jet of water to dislodge them; avoid spraying when flowers are open. |
| Slugs and snails | Irregular holes chewed in young leaves and seedlings, often accompanied by silvery slime trails. | Use physical barriers like copper tape or beer traps, and apply iron phosphate-based pellets if necessary. |
| Failure to set pods | Plants produce abundant flowers but few or no beans, often dropping petals without forming fruit. | Ensure consistent watering during dry spells and plant in a sheltered site to encourage bee pollination. |
| Bird damage | Pecked or missing flowers and young pods, particularly noticeable in varieties with brightly coloured blooms. | Net the plants once flowering begins or switch to a variety with different flower colours to deter birds. |
For step-by-step help, read Controlling Aphids Naturally and Dealing with Slugs and Snails. Or browse the full plant problem solver to diagnose an issue by symptom.
Runner Bean in our guides
- How to Grow Runner Beans in the UK
- Rust on Plants: How to Identify and Treat Garden Rust
- Charles Dowding: Why Mid-June Is the UK's Busiest Sowing Fortnight
- June rain and sunshine set to boost flowering garden plants
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