Scarlet runner bean

About Scarlet runner bean

Scarlet runner bean is a fast, twining vine from the mountains of Mexico and Central America, grown both for its sprays of scarlet flowers, which hummingbirds and bees love, and for its pods and big speckled beans. Vines usually reach 6 to 8 feet in Midwest gardens and can top 15 feet. It sets the most pods in cool summers and fall; hot weather cuts pod set.

Grown as a warm-season annual in every zone; frost kills the leaves. In zones 7 to 11 it can live a few years from its fleshy roots, and northern gardeners can dig the roots and store them in damp sand for winter.

When to plant

Timing is counted from your average last spring frost (and first fall frost). Sow & Tell works out the actual dates for your ZIP code.

Days count from seeding to first pods for named varieties (about 65 to 85 days); flowers start about two months after sowing. Sow 2 to 3 inches deep once soil is at least 50F, or start seeds indoors a few weeks before the last frost and set out after it; put the trellis in at planting.

Soil

Well-drained soil rich in organic matter, kept evenly moist, especially while it flowers and sets pods.

Choose a sunny spot with soil rich in organic matter and set up a sturdy trellis, poles or netting before sowing.

Feeding

Heavy fertilizing gives lots of leaves but fewer flowers and beans; water well during flowering and pod set and mulch to hold moisture.

Harvest

Pick pods young, about 4 to 6 inches long, and use them like snap beans; keep picking so the vine keeps flowering. Older pods can be shelled while the beans are still pale pink, or left on the vine until dry and rattling for dry beans.

Flowers and pods keep coming until frost if you keep picking young pods; the heaviest crops come in cool summers and in fall, since hot weather cuts pod set.

Varieties (15)

Good neighbors

Sweet corn, Winter squash and pumpkin

Arkansas Extension notes it was grown in the Indigenous Three Sisters planting with corn and squash, the corn holding up the vines; that is traditional practice, not a tested pest benefit.

Pests to watch for

Mexican bean beetle, Japanese beetle, Slugs, Rabbits

Diseases and problems

Mosaic viruses, Bacterial blights of beans, Anthracnose, Powdery mildew, White mold

In the kitchen

Slice young pods and boil, steam or saute them; shell half-grown beans and cook like limas; dry beans need a long soak and long cooking. The flowers are edible in salads.

Safety: Raw or undercooked beans contain a lectin (phytohaemagglutinin) that can cause severe nausea, vomiting and diarrhea, so cook dried beans thoroughly and eat raw pods only sparingly (NC State, Wisconsin Extension).

Pets: Not listed by the ASPCA