Ask A Master Gardener – Scarlet Runner Beans; Going Vertical

Photo credit-Susan Mahr.

When endeavoring to attract pollinators such as bees, butterflies, and hummingbirds, it is a good idea to plant in more than one plane. Having short plants, medium plants, and tall plants, give pollinators the opportunity to flit from one plant to another and get to all of the blooms without interference from the leaves and stems.  Adding a climbing flower gives that little extra that the pollinators will appreciate. Scarlet Runner Beans, Phaseolus coccineus, fit the bill nicely.

Used by Native Americas and colonists as a food plant, these beans, native to the mountains of Mexico and Central America, are now more commonly grown as an ornamental plant. In milder climates, they can be treated as a perennial, but in our zone 5a they will be an annual.

Scarlet runner bean plants look very similar to traditional garden green beans. The leaves are dark green with that familiar heart shape. Like a pole bean, they will vine extensively growing up to 15 feet in a warm climate; more likely to 6—8 feet in the Midwest.  Like garden beans, they will grow best in full sun and in rich soil with plenty of organic matter.  They will not tolerate frost, so wait until that danger has passed before planting.  They will germinate best if the soil temperature has warmed to 50°.

Plant the large, colorful violet-mottled-with-black seeds 4—8 inches apart and 2—3 inches deep. They will germinate in 7—14 days.  Provide plenty of moisture until the seeds have germinated and during flower production.  Mulch will help conserve moisture and reduce the need for weeding.  Resist the urge to fertilize since this will result in lush foliage and fewer flowers.

Scarlet runner beans are most commonly grown for the beautiful display of flowers and they do not disappoint. About two months after sowing the seeds, the show begins.  The plants produce an abundance of brilliant red (and occasionally white) flowers similar to other legumes. Up to 20 flowers, each an inch-long, will appear in each cluster along the vine.  The blooms, extremely attractive to bees and hummingbirds, open at sunrise and fade at sunset.  The flowers are followed by 12-inch-long bean pods.  To encourage the plant to continue to flower, pick off the pods and discard.

While scarlet runner beans are generally grown for ornamental purposes, the flowers, bean pods, and seeds are all edible. The flowers have a bean-like flavor and can be used in salads to enhance the flavor, as well as give it a dash of color.

The pods can be boiled, baked, steamed, or sautéed when they are young and tender. They are tougher than standard green beans and many people do not find them palatable because of the rough texture of the skin.

The seeds inside the pods can be allowed to dry in the pod as long as possible in the fall. If frost threatens, pick and bring them inside until they are completely dry and rattle when shaken.  Remove them from the pod before cooking.  These can be cooked as you would any dry bean, by soaking overnight first, then incorporating in your favorite recipe.  Or, simply save some of the seeds for sowing next year and repeating the cycle of beauty in your garden.


Carol Shirk

Certified Master Gardener


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