How to Plant and Grow Scarlet Runner Bean for Its Gorgeous Edible Flowers
Most bean plants are relegated to rows or patches in the vegetable garden. Although they are tasty and healthful, when it comes to looks, well, they didn’t win that lottery. However, the scarlet runner bean is an exception. This gorgeous twining vine produces oodles of colorful blooms throughout the summer, which—if pollinated—form flattened pods that can be eaten like other green beans. The flowers attract pollinators, including bees and hummingbirds, and the blooms are edible; they add color and bean-like flavor to salads.
Scarlet Runner Bean Overview
| Genus Name | Phaseolus coccineus |
| Common Name | Scarlet Runner Bean |
| Plant Type | Vegetable, Vine |
| Light | Sun |
| Height | 6 to 15 feet |
| Width | 3 to 5 feet |
| Flower Color | Red, White |
| Foliage Color | Blue/Green |
| Special Features | Attracts Birds |
| Zones | 10, 11, 7, 8, 9 |
| Propagation | Seed |
Where to Plant Scarlet Runner Bean
A sunny spot with rich, well-drained soil is best for these beans. They are vigorous climbers that need something sturdy to support their upward growth. A fence works well, but you can also grow them on a teepee or trellis. Avoid windy sites because they produce dense leafy growth and can reach up to 15 feet tall, although 6 to 8 feet is more common. Don’t plant them where they will cast shade on other sun-loving plants.
How and When to Plant Scarlet Runner Bean
These beans are easiest to sow directly in the garden after all danger of frost has passed. If you have a short growing season, start your plants indoors four to six weeks before your last predicted frost. Don’t plant them outdoors too early because they are sensitive to cold temperatures. It’s best to wait until night temperatures stay above 50°F before planting seeds or transplanting seedlings.
Sow the seed 2 inches deep and 6 to 8 inches apart. If you start the seeds indoors, plant one or two seeds per small pot, thinning to the strongest seedling. Disturb the roots as little as possible when transplanting. Supply the beans with a support for them to climb at planting time. Strings, netting, a fence, or poles are all good options.
Scarlet Runner Bean Care Tips
Growing this heat-loving South American native is easy, and its growth rate is fast once warm weather sets in.
Light
The sunnier the spot, the better scarlet runner beans grow. Site them where they will get at least six hours of full sun each day.
Soil and Water
Scarlet runner beans thrive in a neutral to slightly acidic, organically rich soil. While they need consistent moisture, the soil should be well-drained and not remain soggy. Mulching helps retain moisture between waterings.
Temperature and Humidity
These heat-loving beans are sensitive to cold, and seeds germinate poorly when planted in cold soil. The plants will die back to the ground with the first hard frost in the fall. They grow quickly in warm weather, but pod formation slows when temperatures exceed 90°F and picks up again when temperatures drop. They tolerate a range of humidity levels, but moderate humidity is best.
Fertilizer
Working compost or well-rotted manure into the soil prior to planting may be sufficient to supply nutrients for these beans. Over-fertilizing can stimulate leafy growth at the expense of flowering and pod formation. If the beans seem to need a mid-season boost, side-dress them with a slow-release organic fertilizer.
Pruning
The only pruning necessary with scarlet runner beans is pinching the tops to control their height when they reach the top of their support.
Potting and Repotting
Growing scarlet runner beans in a container is easy and an excellent option for small gardens. Fill a large, heavy container (10 gallons or 30 inches wide is a good size) with well-draining, rich soil. Sow the seeds 2 inches deep and 6-8 inches apart and water well. Add stakes or a trellis to support the vines as they grow. Position the container in an area of the garden that receives at least 6 hours of sun daily. Ensure some pollinator-attracting flowers are planted nearby to pollinate the bean flowers.
This plant is often grown as an annual, but in USDA Zones 7-11, it is a short-lived perennial plant. Unless the plant’s root base outgrows the container, it doesn’t require repotting, although it benefits from the addition of compost in spring.
Pests and Problems
Although easy to grow, scarlet runner beans are susceptible to a few pests. Slugs and rabbits might nibble on young plants. A wire cage protects emerging seedlings from rabbits, and slug traps help control slugs. Mexican bean beetles, Japanese beetles, aphids, and leafhoppers are sometimes a problem. Hand-picking or a hard spray of water will reduce populations of these pests.
Powdery mildew, which forms a dusty layer on leaves, is sometimes a concern, but it can usually be avoided if you don’t overcrowd the plants to allow for good air circulation. Remove infected leaves if you notice them, and don’t put them in the compost pile.
How to Propagate Scarlet Runner Bean
Although roots may overwinter in frost-free climates, scarlet runner bean is nearly always grown as an annual from seed. The seeds are simple to harvest from existing plants, and they store well in a dry, warm place until the following spring. It is best to direct sow the seeds in the garden after the soil has warmed to at least 50°F. You can start the seeds indoors a few weeks before moving them into the garden, but avoid disturbing the roots when transplanting.
Types of Scarlet Runner Bean
‘Scarlet Emperor’
‘Scarlet Emperor’ is an heirloom variety that produces crimson flowers that are hummingbird magnets. The vines grow to 10 feet tall if support is available. The pods can be harvested after about 70 days for cooking as snap beans or allowed to dry on the vine. Once dried, the large raspberry seeds with black streaks can be soaked, cooked, and enjoyed all winter.
‘Painted Lady’
Another heirloom, ‘Painted Lady’ bears two-toned flowers with bright coral upper petals and blush pink to white lower petals. The vine grows 8 to 10 feet tall with a support. The plant is extremely attractive to hummingbird moths and hummingbirds.
‘Black Knight’
In addition to its cheerful scarlet flowers, ‘Black Knight’ produces purple-black pods that can be cooked and eaten as snap beans. When they are allowed to mature and dry on the vine, the obsidian-colored seeds can be saved for winter dishes. It matures in 65 to 80 days.
‘Sunset’
The flowers of ‘Sunset’ variety are peachy pink, and the pods are bright green. This variety matures in 65 to 70 days but continues to bloom until the weather turns cold in fall.
The raw pods and seeds of scarlet runner beans are mildly toxic to humans. Always cook the pods before eating them.
Scarlet Runner Bean Companion Plants
Scarlet runner bean makes a lovely vertical accent when grown on a trellis or teepee. It can be a feature of the vegetable garden or included in a mixed annual border. Because flowers do not self-pollinate, pollinator-attracting plants are excellent companion plants if you plan to harvest pods.
Annual Salvia
Annual salvia is an easy-to-grow, long-flowering addition to any garden, where it adds bright colors and fabulous forms. It attracts pollinators such as bees, butterflies, and hummingbirds.
Zinnias
Zinnias come in many colors and sizes, providing options for placement. They attract pollinators, including butterflies, moths, bees, and syrphid flies, while adding vivid visual appeal to any garden in need of a bold splash of color.
Black-Eyed Susan
Black-eyed Susan bears large yellow flowers with dark centers in mid to late summer. It grows 2-3 feet tall, and attracts pollinators. The yellow flowers provide a lovely contrast to the scarlet blooms and deep green foliage of the scarlet runner bean.