The Scarlet Runner Bean: Sowing, Growing and Harvesting

Description and Botany

Although little known in France, the runner bean is nonetheless the third most cultivated bean species worldwide. In many South American or Mediterranean countries, people enjoy runner beans either as long green pods or in the dried form of its seeds.

Botanical illustration

A member of the Fabaceae family, Phaseolus coccineus boasts a multitude of varieties, all descended from a wild variety still found in the humid marshlands of northern Mexico. Indeed, Central America is where the runner bean originates, specifically Honduras, Guatemala and Mexico. Archaeological excavations have uncovered seeds of the wild variety in Durango and Puebla, as well as in the caves of Tamaulipas in Mexico, where the Anahuac peoples gradually domesticated it.

The runner bean likely made its way to European soil in the 16th century, brought by the Spanish, much like our green beans (Phaseolus vulgaris). By the 18th century, it had become a staple in English gardens, where it adorned spaces with its strikingly bright flowers. This very conspicuous red hue attracts hummingbirds inhabiting the deep valleys of Mexico’s mountains. One American ornithological site even lists the runner bean among the plants most visited by hummingbirds. In our regions, we’ll have to make do with bumblebees, honeybees, carpenter bees and other pollinating insects that also appreciate the runner bean’s flowers. These insects, in fact, ensure pollination and, consequently, fruiting.

The runner bean is a perennial plant, cultivated as an annual in our climate due to its lack of hardiness. It features a tuberised taproot, similar to dahlia tubers. These fleshy roots are rich in starch (but also contain toxic substances) and are even part of the diet of certain Central American ethnic groups.

This ornamental and edible plant has a climbing habit. Its voluble stems twist and twine around any support provided, whether a trellis, wire mesh, pergola or any other type of fence. They can reach up to 4 metres in length, though 2.5 to 3 metres is more typical.

Its deciduous foliage is medium green. The alternate, trifoliate and ovate leaves taper to a point (acuminate), resembling a heart shape. They feature light-coloured veins. Some varieties have slightly purplish undersides.

As previously mentioned, the flowering is remarkable and alone justifies inviting the runner bean into your garden. From June to September, the plant becomes covered in clusters around 20 centimetres long, composed of papilionaceous flowers in a bright scarlet-red hue. Other varieties bloom in red and white, orange or white.

The flowers of the runner bean can take on scarlet-red, orange or bicoloured hues

These flowers give rise to long, edible green pods, flat at first, then plump as they fill with seeds in two dehiscent valves, displaying varied colours depending on the variety. White marbled with red, pink speckled with red, bronze, brown, violet-black… these seeds boast strikingly original hues.

But their uniqueness doesn’t end there, as runner bean seeds are said to be hypogeous in germination. Practically speaking, unlike common beans, during germination, the cotyledons remain underground while the stem emerges, already topped with the first leaves. In common beans, the cotyledons emerge above ground, attached to the stem.

During germination, unlike common beans (right), the cotyledons remain underground.

The runner bean likely inherited this trait from its montane origins, at altitudes of around 2000 to 3000 metres. Similarly, the seeds germinate at relatively low temperatures, around 15 to 17°C. It takes approximately 4 to 5 months for the seeds to reach ripeness.

The different varieties of runner beans

Red-flowering varieties

Bi-colour flowering varieties

White-flowering varieties

Runner Bean Scarlet Emperor - Ferme de Sainte Marthe Seeds

This variety features long stems of nearly 4m with bright red flowers and purple-black speckled seeds. The pods reach 30cm. A very vigorous variety, perfectly suited to cool climates.

• Flowering time June to September
• Height at maturity 3 m

See the product sheet

Runner Bean Prijswinner - Dutch Red

This runner bean variety produces long clusters of scarlet red flowers and pods around 30cm long

• Flowering time June to August
• Height at maturity 4 m

See the product sheet

Runner Bean Enorma

Growing to 3m tall, this runner bean variety flowers in orange-red and produces pods 25-50cm long

• Flowering time June to September
• Height at maturity 3 m

See the product sheet

Runner Bean Spanish Bean St. Georg

This variety features red and white flowers, flat pods nearly 30cm long, and brown seeds marbled with black

• Flowering time June to September
• Height at maturity 4 m

See the product sheet

Runner Bean Hestia

This dwarf variety with coral and white flowers reaches just 40-50cm tall, yet produces delicious pods

• Flowering time June to September
• Height at maturity 45 cm

See the product sheet

Runner Bean Moonlight

A lovely white flowering variety producing very tender, sweet pods

• Flowering time June to September
• Height at maturity 4 m

See the product sheet

Sowing Scarlet Runner Beans

Where to Sow?

Spanish beans are not particularly demanding when it comes to growing conditions. A good, rich, well-drained garden soil is perfectly sufficient. However, they also tolerate cooler soils. The soil should be loosened and cleared of weeds and stones.

Spanish beans enjoy a sunny position except in regions with hot summers, where they will need partial shade. On the other hand, provide them with a sheltered spot away from strong winds.

When to Sow?

Outdoors, Spanish beans can be sown once the risk of frost has passed—mid-May north of the Loire, or as early as April further south. Native to the mountains of Central America, Spanish beans germinate at temperatures between 15 and 20°C.

You can also opt to sow indoors in regions with longer winters. Since Spanish beans have a fairly long growing cycle (around 90 to 100 days from sowing to harvesting immature pods), you can sow as early as March in a heated cold frame. Then, simply transplant them once the frosts are over.

How to Sow?

Like other beans, Spanish beans are sown in clusters of 3 to 4 seeds, spaced 50 cm apart. If sowing in rows, leave at least 80 cm between each furrow. The seeds should be planted about 5 cm deep.

Keep the soil moist until germination, which occurs around ten days after sowing.

The care of runner beans

The priority for runner beans is providing supports if you’ve decided to grow them in the vegetable garden. You can also choose to let them climb along a trellis or over a pergola to shade a terrace. Either way, in the vegetable garden, supports are essential. Several solutions are available to spark your imagination: teepee or A-frame structures to amuse children, using strings stretched between stakes, concrete reinforcing bars or bamboo poles, with trellis netting, or even chicken wire. The stems easily twine around their supports.

There are countless ways to support runner beans

Watering should be regular during hot weather, especially when flowers are developing into pods. Regular watering also prevents flower drop. To reduce watering needs, don’t hesitate to mulch. Similarly, hoeing should be consistent.

Earthing up is also recommended when the young plants reach 15 to 20 cm.

While less susceptible to common bean diseases, runner beans may still suffer from aphid infestations which can weaken the plant. Natural predators like ladybirds help manage the infestation. Virginie also shares her secrets for identifying and treating aphids.

As for young plants, they’re highly sought after by slugs. Feel free to check out the 7 ways to effectively and naturally combat these voracious pests.

Good Companion Plants for Scarlet Runner Beans

As a Fabaceae, in the vegetable garden, the runner bean thrives alongside potatoes, beetroot, carrots, aubergines, sweetcorn and squashes. However, planting alliums (garlic, shallots, onions and leeks) nearby is not recommended, nor is planting peas.

If you’re growing runner beans purely for ornamental purposes, pair them with morning glories, sweet peas, corkscrew flowers (Phaseolus caracalla) or nasturtiums.

When combined with morning glories, sweet peas and nasturtiums, runner beans create a beautiful colourful display or can cover an unsightly wall.

The harvest, storing scarlet runner beans

There are two periods for harvesting runner beans. The first occurs when the pods are formed in the same way as other beans. Depending on the variety, the pods are picked when they reach 15 to 20 cm in length. Harvest before the seeds form, as the pods quickly become stringy. As long as they are flat, the pods are excellent. When they grow larger, they can be cut into pieces for cooking.

If you harvest your beans regularly, the plant will be encouraged to produce new pods. These immature beans can be stored for 5 days in the refrigerator or blanched and frozen.

Runner beans are harvested at the immature stage when they are still flat or dry.

Around 4 to 5 months after sowing, usually around October, runner beans can also be harvested when the pod is dry. This yields beautifully coloured dried beans, often as large as a €2 coin.

Scarlet Runner Beans: From Garden to Plate

Scarlet runner beans can be eaten like other beans. Picked very young, they can be prepared like fillet beans or mangetout, steamed or boiled in water, then garnished with tomatoes, onions or garlic. When larger, cut them into sections for cooking. They can be stir-fried in a wok with parsley.

When dried, scarlet runner beans can be used in soups, purées, or crushed with a Spanish-style tomato sauce. It’s recommended to soak them in water overnight to make cooking easier.