Runner Bean

Sow seed directly outdoors after all danger of frost has passed and the soil has warmed to at least 50–60°F, planting seeds 1–3 inches deep and spacing them roughly 4–8 inches apart; germination takes about a week to three weeks. Because runner beans are twining vines that can reach 8 to 15 feet, install poles, a trellis, netting, or a teepee of canes at sowing time so the plants have something to climb from the start.

Grow in full sun in fertile, organically rich, well-drained soil that stays consistently moist, and provide abundant water especially during flowering and pod set; mulching helps conserve moisture. Avoid heavy fertilizing, since it pushes lush foliage at the expense of flowers and beans, though working compost into the soil before planting and again mid-season supports steady production. Flower and pod set can slow in very hot summer weather and resume as temperatures cool toward fall.

Runner beans can be affected by mosaic viral disease, bacterial blight, anthracnose, powdery mildew, and white mold, along with foliage feeding from Mexican bean beetles and Japanese beetles. Young, newly established seedlings are also vulnerable to slugs and rabbits and may need protection until they get going.

Pick the green pods while still young and tender, roughly 3 to 5 inches long, since older pods left on the vine grow tough and fibrous; keeping pods picked encourages the plant to keep flowering. Edible flowers can be harvested as unopened buds or fully open blooms once they show strong color, but they last only a day or two on the plant, and open flowers should be used right away while unopened buds can be held a couple of days refrigerated on a damp towel.

To save seed for the next planting, leave pods on the vine as long as possible until they turn tan or brown, dry, and brittle with the seeds rattling inside; if frost threatens, mature pods can be picked and brought indoors to finish drying. Break open the dried pods, then dry the seeds further in a cool, dark, well-ventilated spot before storing them in an airtight container, where they can remain viable for several years.

Culinary: The young green pods, the mild and crunchy flowers, and the young leaves are all edible, and the seeds can be shelled and cooked fresh like lima beans or dried for later use; in Mesoamerica the plant's starchy tuberous roots are also eaten. Raw or undercooked mature seeds carry a mild toxin that is neutralized by thorough cooking, and dried seeds require long soaking and cooking, though both pods and beans lose their bright color once cooked.

Ornamental: The vine is widely grown to cover trellises, arbors, fences, and other supports, valued for its rapid climbing habit and long season of scarlet, white, or bicolored blooms that attract hummingbirds, bees, and butterflies.

Runner bean is native to the mountain regions of Mexico and Central America, growing at higher elevations than the common bean, and was most likely first cultivated in the highlands of Mexico and Guatemala around 2000 BC. Ancient bean pod remains found in a cave in northeastern Mexico may be as old as 6,000 years, though it remains debated whether these represent a wild or already domesticated form. Wild, small-seeded perennial vines of the species can still be found today in Mexico and Guatemala, climbing over other vegetation in cool, partially shaded sites. By the 1600s the crop had reached English and early American gardens, initially valued as food before becoming primarily an ornamental in North America while remaining a food crop in cool-summer parts of Europe.