Runner beans (Phaseolus coccineus), also known as scarlet runner beans, are grown both for food and ornamental value. The vines produce showy red flowers in the summertime and into fall. They give way to edible pods that are either green or purple. Both the flowers and the green leaves, which are 3 to 5 inches long and composed of three ovate leaflets, are edible as well.
While this plant is a perennial, growing runner beans as an annual outside of their hardiness zones is common too. Runner bean seeds should be planted in the spring after the threat of frost has passed; they have a rapid growth rate. Note that while you can eat the beans of runner beans, eating them uncooked can be toxic to people and animals. So be mindful of runner bean plants around children and pets.
|Common Name||Runner bean, snap bean, scarlet runner bean, multiflora bean, butter bean|
|Botanical Name||Phaseolus coccineus|
|Plant Type||Perennial, vegetable|
|Size||8–12 ft. long, 3–5 ft. spread|
|Sun Exposure||Full sun|
|Soil Type||Loamy, moist, well-drained|
|Soil pH||Acidic, neutral|
|Bloom Time||Summer, fall|
|Hardiness Zones||7–11 (USDA)|
|Native Area||Central America|
|Toxicity||Toxic to people, toxic to pets|
How to Plant Runner Beans
When to Plant
Frost will kill runner beans, so wait to plant in the spring until there is absolutely no more frost in the forecast. This will vary by region. You can even wait until early summer. Or you can start your plants indoors around four to six weeks prior to your area's projected last spring frost date.
Selecting a Planting Site
Pick a planting site with good drainage and lots of sun. Avoid planting near members of the onion family, as they can inhibit the growth of beans. Container growth is also an option.
Spacing, Depth, and Support
Seeds should be planted around 6 inches apart and 2 inches deep. Leave around 2 inches between rows. You will need to add supports for your beans at the time of planting. Bamboo canes are a common support used, but you also can use a trellis or other structure.
Runner Bean Plant Care
Runner beans need full sun, meaning at least six hours of direct sunlight on most days.
A loose, organically rich, loamy soil with a slightly acidic to neutral soil pH is ideal for runner beans.
Runner beans require consistent moisture, but they never should be sitting in soggy soil. Plan to water as often as needed to keep the soil lightly moist but not waterlogged.
Temperature and Humidity
These plants are not cold hardy and will die when the first frost arrives in the fall. In temperatures above 90 degrees Fahrenheit, bean production will slow. But it should pick up again once the weather cools. A moderate humidity level is best for the plants.
It’s ideal to mix a layer of compost into the soil in the fall prior to planting. Then, give your beans a side dressing of compost midway through the growing season to encourage vigorous production through fall.
Insects and the wind help to pollinate runner beans. Pollination won't be as productive in hot temperatures.
Types of Runner Beans
There are several types of runner beans available that vary somewhat in appearance, including:
- 'Hestia': Is a dwarf bush variety that begins flowering early
- 'Moonlight': Is self-pollinating and has white flowers
- 'Painted Lady': Has red and white flowers and is tolerant of hot weather
- 'Prizewinner': Is very prolific
- 'Sunset': Has pale coral flowers
Runner Beans vs. Green Beans
Runner beans are not the same as green beans, though they are from the same plant family. Green beans (Phaseolus vulgaris) are generally more round and plump than runner beans (Phaseolus coccineus), but they are used in similar ways in cooking.
Harvesting Runner Beans
What month you pick runner beans depends on when they were sown, but the plants will typically start producing harvestable beans around midsummer. In general, you’ll see flowering approximately four to five weeks after planting and harvestable beans approximately 60 to 75 days after planting. And you should be able to harvest until frost arrives in the fall.
You can pick pods when they're young and tender to cook or allow them to fully mature to shell or dry. Check for harvestable beans every few days to keep the production going. The pods are ready when you can snap them cleanly from the vine.
You can store your beans in the refrigerator for about a week for cooking. For drying, set them in a single layer in a well-ventilated area to thoroughly dry, and then store them in an airtight container.
How to Grow Runner Beans in Pots
Container growth can be a good option if you don't have garden space. But runner beans need a fairly large container to grow well. The container must be heavy, so it can support stakes for the beans to climb. Opt for a container that's at least 30 inches wide and 18 inches deep. The container must have drainage holes. Unglazed clay is a good material, as it will allow excess soil moisture to evaporate through its walls.
Pruning isn't an extensive chore with runner beans. But you can pinch the tops once they've twined to the top of their supports. That way, they can focus their energy on producing flowers and pods rather than growing more foliage.
Propagating Runner Beans
Runner beans are best propagated via saved seeds. This is an inexpensive and easy way to create more plants from a variety you particularly liked. Plus, if you live in a climate where you can only grow runner beans as annuals, you’ll ensure that you have crops for the next year. Save the seeds in the summer or fall for planting the following spring. Here’s how:
- Let some seed pods fully dry and mature on the plant. They will become brittle.
- Harvest the dried seed pods, and break them open to release the seeds.
- Let the seeds thoroughly dry in a cool, dark, well-ventilated area. Then, store them in an airtight container.
How to Grow Runner Beans From Seed
You can direct sow or start the seeds indoors four to six weeks before you plan to move them out. Beans grow quickly and do not transplant well, but if you have a short season and want to get a head start, sow them inside in peat or paper pots. Wait until the ground has warmed before planting outside.
Plant two to three seeds at the corner of each pyramid-like support or space seeds six inches apart along a trellis. They are quick to germinate. Train them along their support to get them started. Use twine or twist ties to loosely attach early stems to the trellis. Once started the tendrils and vines will begin to cling and climb on their own.
Potting and Repotting Runner Beans
If you started your runner beans in a small pot, repot the seedlings once they’re about 3 inches high in a container that can fit their mature size. Another option is simply to start them in the large container, so you don't have to disturb their roots with repotting.
If you live in an area that doesn't get frost over the winter, you can leave your bean plant roots in the ground after the foliage depreciates. A layer of mulch can help to insulate the roots and retain soil moisture ahead of new growth in the spring.
Common Pests and Plant Diseases
Runner beans don't usually have major problems with pests or diseases. Some pests that might affect the plants include Mexican bean beetles, Japanese beetles, leafhoppers, aphids, slugs, and snails. Potential diseases include mosaic virus, blight, anthracnose, and powdery mildew.
Are runner beans easy to grow?
Runner beans are fairly easy to grow, as long as you provide them with plenty of sun and moisture. They also must be protected from frost.
How long does it take to grow runner beans?
After planting, it will take around two to three months for your runner beans to start producing a harvest.
Can you grow runner beans indoors?
Runner beans are not an easy crop to grow indoors. They require lots of sunlight to flower and produce pods. They also need insects for pollination.
Phaseolus coccineus. NC State Extension.
Plant Lectins. Cornell University Department of Animal Science.