Runner beans They’re eager growers, so how do you stop them getting out of hand?

WHEN it comes to versatility, it’s hard to see past the runner bean – people have been using almost every part of Phaseolus coccineus for thousands of years. The beans have been grown as ornamentals and the crimson flowers, pods, beans and even tubers have been treated as food. Only the leaves were left for slugs.

There’s evidence beans were first domesticated in Mexico 4,000 years ago and remains of its wild relative go back another 5,000 years. Although Central Americans used runners as a food crop, they were grown as ornamentals in 16th-century Spain. The English were equally besotted with the scarlet flowers when Chelsea Physic Garden’s head gardener John Tradescant introduced it to the court of Charles I.

The original scarlet runners were short day plants and wouldn’t have developed flower buds until late August or early September when nights were at least 10 hours long, too late for pods to develop. No wonder it took another hundred years for the penny to drop: the pods, if you got them, were pretty tasty. Gardening writer and curator at Chelsea, Philip Miller, mentioned this when describing the plant’s many virtues in The Gardener’s Dictionary 1754. They also coped with the air pollution caused by sea coal, and were “cultivated in balconies and produce flowers as well”.

Miller also noted that “they grow to a great height and are supported by sticks and string”. Since the plants scale 2m-high frames and throw out a mass of side shoots, Miller’s sticks and strings would have had their work cut out to support the weight.

If you have too large a crop to munch through, there are two solutions. You can reduce the number of beans by picking some flowers for edible decoration for a salad. Or you can slow down the bean production by letting large stringy pods grow on. Pick as many small pods as you can handle and let the ones you’ve missed give you an extra harvest. I’ve found my frozen runner bean pods are pretty rubbery, but, like peas, the beans freeze well.

I spend an hour constructing a robust bean frame, and always aim to use it two or even three times. I know I’m breaking the first rule of veg gardening: rotate the crops to keep vegetables healthy.

Unlike most vegetables, runner beans are perennials. But, since they’re frost-tender, you have to treat them as annuals. They grow naturally in the same site for several years, so it’s safe to use the ground again without a build-up of pathogens. In fact, there’s strong evidence that runners form a symbiotic relationship with rhizobia in the soil and this persists for more than one season. The bacteria extract nitrogen from the soil which they fix to the plant roots in exchange for proteins and carbohydrates.

It is possible, albeit difficult, to treat runners as perennials. In warmer parts of the UK, you may get away with cutting the vines down and leaving the tuber in the ground. Cover it with a thick mulch to act as a winter duvet. When the plant starts growing in spring, protect against late frosts and enjoy an earlier than usual crop.

More realistically for Scotland, cut the vine down after the first frost. Lift the tubers carefully and store them in a cool, frost-free shed. Start by upturning the tubers to let them dry out. After a few weeks, put the tubers in a tray of dry sand, covering all but the small plant stem.

In spring, pot up the tubers and plant them out when risk of frost has passed. You’ll get an earlier but smaller crop than you’ll get from freshly sown runners.

PHOTOGRAPH; PETER MacDIARMID/GETTY IMAGES The solution to a glut of runner beans is to store them in the freezer, although the pods don’t cope with sub-zero temperatures as well as their contents