Vegetable · Fabaceae
Runner Bean
Phaseolus coccineus
Long green pods and scarlet, white, or pink-and-white flowers ride fast twining vines that climb until frost.
Full sun
Every 3–7 days
50–77°F · 10–25°C
65–75 days
Overview
The runner bean grows as a fast twining vine, its stems winding upward around any support within reach. It is a member of the bean family, and where winters stay mild in zones 7 to 11 the fleshy tuberous roots hold on below ground and send the plant up again, though most see only the annual growth. In a single season those twining stems stretch 6 to 10 feet overhead.
Through summer and into fall the vine carries clusters of flowers in scarlet, white, or a painted red-and-white, the color set by the variety. Each pollinated bloom lengthens into a long green pod, smooth and tender while it is young. Left on the vine, that pod hardens and fills with fiber, and the seeds inside swell into the mature beans kept for shelling.
Up close the plant shows its legume nature: down in the roots, Rhizobium bacteria gather nitrogen, which is why so little feeding is needed. The stems climb by twining around their support rather than by leaning on it. Heat is the one thing the flowers cannot take, dropping from the vine before they set when the days turn hot.
Care
The short version: set runner beans in full sun on a tall support, keep the fertile, well-drained soil evenly moist near 1 inch of water a week, and feed lightly, since the roots gather their own nitrogen.
Light
Runner beans stand in full sun and take no shade. Bright, direct light is what pushes the twining stems upward fast and keeps the flowers coming. Give them the most open, sunlit ground you have.
Water
Keep the soil evenly moist with about 1 inch of water a week, most of all as the flowers open and the young pods form. Sandy, quick-draining ground dries sooner and wants water more often. Steady moisture holds the blooms on the vine when the air turns warm.
Soil
The roots run deep into fertile, well-drained loam at pH 6.0 to 7.0. Turn in a little compost before sowing, and the thick root system takes hold from there.
Temperature
The vine holds its flowers between 50°F and 77°F (10°C to 25°C), the cool range it prefers. Once the heat climbs above that, the blooms loosen and fall before they can set into pods.
Humidity
Everyday moisture in the air, around 40% to 70%, is all the plant meets and all it needs. A little space between the vines lets air slip through the leaves.
Feeding
Feeding stays light, because the roots fix their own nitrogen. A small dose of 5-10-10 at planting is enough, and too much nitrogen swells the leaves while the pods thin out.
Pruning
Little cutting is called for. When a stem reaches the top of its support, pinch off the soft growing tip to send out side shoots and more pods, and clear the spent pods as they finish.
Repotting
This is no pot plant. The seed goes straight into garden soil at the base of a tall support, where the deep roots have room to spread.
Size & spacing
The twining stems climb 6 to 10 feet (1.8 to 3 m) while the plant keeps a narrow base, only 12 to 24 inches (30 to 60 cm) across. Set a tall, firm support and leave space for air to pass through the leaves.
When to plant
The vine will not stir until the soil is warm. Once the last spring frost has passed and the ground holds at 50°F to 60°F (10°C to 16°C), the sown seed breaks the surface, and the first slender green pods hang ready about two months later, on until frost.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: Optional: 2-3 weeks before the last spring frost in biodegradable pots to avoid root disturbance.
- Plant: After the last spring frost, once soil is at least 50-60°F (10-16°C).
- Harvest: Flowers from early-to-mid summer until frost; harvest young pods (10-15 cm / 4-6 in) about 65-75 days after sowing.
Hardiness
USDA hardiness zones: 7–11
Temperature: down to -18°C
Troubleshooting
The runner bean wears its troubles plainly, on the flowers, the pods, and the leaves. A dropped bloom, a fiber-filled pod, or a leaf worked to lace each tells you what is wrong. Read the plant itself and the entries below point to the cause.
Flowers loosen and fall in heat without pods
The blooms dropping from the vine are blossom drop, brought on by heat. When the days pass 80°F to 90°F (27°C to 32°C), the pollen fails and the flowers let go before a pod can form. Cool, evenly watered roots and a little afternoon shade in a heat wave hold the plant until temperatures fall and pods set again.
Fix:
- Keep soil evenly moist and mulch to moderate root-zone temperature
- Provide light afternoon shade during heat waves
- Wait for cooler weather, when pod set typically resumes
Leaves are eaten to lace or curled tight
Leaves reduced to lacy skeletons with yellow grubs on the underside mark the Mexican bean beetle, while shoot tips curled tight over small soft bodies mark aphids. Pick off the beetles, the grubs, and the orange egg masses, wash the aphids away with a hard spray of water, and turn to insecticidal soap only when the numbers climb. Watch the plants closely, drape row fabric over the young ones, and let lady beetles feed among them.
Fix:
- Hand-pick beetles, larvae and egg masses
- Dislodge aphids with a strong spray of water
- Apply insecticidal soap to heavy infestations
Pods harden with strings and fiber
A pod left too long turns over-mature, its wall thickening with the fibers and strings that make it snap coarsely rather than crisply. Picked young at 4 to 6 inches (10 to 15 cm), and checked every 2 to 3 days, the pods stay smooth and tender. The ones that harden still give up their swollen seeds for fresh or dried beans.
Fix:
- Harvest pods young, at 10-15 cm (4-6 in)
- Pick every 2-3 days to catch pods at peak tenderness
Toxicity
The green pods and cooked beans are good to eat, and the growing vine is no poison to pets or livestock. It is the hard, raw mature seed that carries the risk, holding a lectin called phytohaemagglutinin that can upset a stomach. Cook the dried beans through, and keep the raw seeds from a cat or dog.
Toxic to
Cats · Dogs
Safe for
People · Horses · Rabbits · Livestock · Birds
Cats Caution
Cats face no listed poison in this plant, and most leave the vine alone. The raw mature bean is the exception, its lectin able to bring on vomiting or diarrhea if a cat swallows a few, so keep the hard dried seeds out of reach.
Dogs Caution
Runner beans are no known poison for a dog, though a dog that gulps down raw dried beans may take an upset stomach from the same lectin. Cooked pods and beans go down fine, so only the raw mature seeds need shutting away.
Horses Safe
A grazing horse meets nothing harmful in the growing plant. Quantities of raw dried beans are best kept back, as with any legume, but the leaves and pods themselves hold no toxin.
Rabbits Safe
Rabbits can strip the foliage without harm. Only the raw mature seeds carry the lectin seen in other animals, so leave them the leaves and the young green pods.
Livestock Safe
Cattle, goats, and sheep take no harm from the living plant. The single exception is a quantity of raw dried beans, which belong cooked rather than fed raw.
Birds Safe
Backyard birds and poultry come to no harm around runner beans. Only bulk raw dried beans trouble the gut, while the green pods and the foliage are safe.
People Safe
For people, the cooked pods and beans are safe, familiar food. The raw mature bean stands apart, holding phytohaemagglutinin, so the dried seeds are cooked all the way through before eating.
Raw or undercooked mature (dry) seeds contain phytohaemagglutinin, a lectin that can cause nausea, vomiting and diarrhea if eaten in quantity; cook seeds thoroughly. Young pods, cooked, are safe.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
United Kingdom
Animal PoisonLine: 01202 509000 (fee applies)
Australia
Animal Poisons Helpline: 1300 869 738
Varieties
A few runner beans stand apart, told mostly by the color of their flowers and their seeds. These are the named types to know by sight.
Scarlet Emperor
An heirloom bearing scarlet flowers that ripens in about 75 days and hangs long green pods in heavy flushes.
Painted Lady
An ornamental type carrying red-and-white bicolor blooms prized as much as its pods.
White-flowered (e.g. 'Czar' / 'Albus')
A dual-purpose type with white flowers and large white seeds, good as a fresh green pod or a dried shell bean.
Companions
Runner beans shine in the Three Sisters planting, climbing the corn for support and feeding nitrogen back to it and the squash sprawling below.
Plant near
corn: In the Three Sisters planting, corn stalks give the climbing beans a natural support while the beans fix nitrogen for the corn.
squash: Part of the Three Sisters; sprawling squash shades the soil and deters pests while the beans climb the corn and fix nitrogen.
How to propagate
The runner bean starts from seed pressed straight into warm ground. It sprouts and climbs on its own, with no special handling.
SeedEasy
Direct-sow outdoors after the last spring frost once soil reaches at least 50-60°F (10-16°C). · Germinates in 7-14 days; begins flowering about two months after sowing.
Press the seeds 1 to 1.5 inches (2.5 to 4 cm) deep at the base of a tall support, once the frost has passed and the soil has warmed to 50°F to 60°F (10°C to 16°C). Shoots break the surface in 7 to 14 days, and flowers open about two months later, so an indoor start of 2 to 3 weeks buys only a little time. Where winters stay mild, the fleshy tuberous roots can be dug in fall and held over for an earlier crop the following year.
Myths
Runner beans are poisonous and unfit to eat.
The cooked young pods are a plain vegetable eaten the world over. Only the raw or undercooked mature dry seed holds trouble, carrying phytohaemagglutinin that can upset the stomach. Cook the dried beans through and they are safe.
Runner beans need heavy nitrogen to crop well.
Like every legume, the plant draws nitrogen from the air through Rhizobium bacteria in its roots and asks for little feeding. Heavy nitrogen swells the leaves and starves the pods, trading the crop for greenery.