Plant Profile- Snake Bean

It isn’t very often I get thoroughly surprised by a crop, but when it happens it brings a lot of joy. I had grown snake beans a few times previously, hoping they would be a useful crop during our difficult summers, and found them to be a bit disappointing. Our spring is usually quite dry, often continuing into early summer until the first monsoon rains arrive. Most warm weather vegetables need a lot of water to perform, so struggle to get going early enough in spring to make a difference to the summer vegetable cropping. By the time the rain arrives there isn’t enough hot weather left for most varieties to perform for long, so waiting to sow until the rains come usually doesn’t work. The climbing snake beans I had originally grown germinated reluctantly in the dry spring ground, climbed their trellises, fruited prolifically when the rains arrived and then seemed to lose interest in living. All that work building a trellis for them to produce mediocre beans in one great flush was off-putting. The climbing snake beans were obviously developed for high turnover market gardens, making them not ideal for home gardeners that prefer long gradual harvests. Staggered sowings just saw our friendly pod sucking bugs move in, causing the beans to become warped and weird tasting.

It was a bit of a pity but in keeping with my experience of a much broader trend. During the domestication of our crops they are often put through a series of genetic bottle necks in pursuit of improved qualities for our convenience, but often resulting in lower plant vigour and pest and disease resistance. The first stages often involve breeding out defence chemicals or spines to make cooking and harvesting easier, setting the stage for pests and diseases to go unchecked. For legumes the original crop is normally suited for use as a dry bean. In the case of snake beans the original domesticated form was as cow peas (Vigna unguiculata), also known as black eyed peas in one of their many colour forms. These staple legumes grow much more vigorously than vegetable snake bean forms and I had high hopes of them being a viable crop, but the pod sucking bugs put an end to that idea. The genus Vigna contains other useful legumes such as mung beans (V. radiata) and adzuki (V. angularis), along with more obscure and less domesticated species that might warrant further trials. The dry bean form was more narrowly selected for varieties that have tasty green pods, the snake beans we know today. The original climbing forms were also selected into dwarf bush forms, to make cultivation and harvesting easier. Kidney beans and peas have gone through similar processes of dwarfing and vegetablisation, and are pretty universally made weaker every time this happens.

So based on this experience I wasn’t expecting much from bush snake beans, though being a lazy farmer I couldn’t resist the appeal of not building trellises. To my surprise the original variety grew just as vigorously as bush cowpeas and by regularly picking the immature pods the pod sucking bugs never seemed to get established or cause much damage. They seem to like living higher off the ground so the low bush form, combined with the regular removal of pods, seemed to mostly fix the problem. Even better the bushes continued to set pods from late spring to mid autumn provided I picked every day or two, unlike the climbers which only gave one flush. The pod sucking bugs can ruin seed that is saved for next season, but allowing the first pods to mature first before they discover the patch seems to solve the problem and gives extra vigorous seed. As the pods mature they swell and become puffy, and once they turn slightly yellow should be picked and the seed removed for drying. During humid weather then tend to mould in the pod if left too long.

Over time I acquired a different form of bush snake bean that is a little more upright, and I consider the flavour and vigour to be not as good as my first form. I also recently was gifted a red podded form that is weaker again, but has managed to produce during this remarkable drought. I will keep growing all three forms together hoping for some natural hybridisation by our many species of native bees. If I get impatient then the fiddly job of hand pollination is an option. I suspect the bush snake beans are a separate subform of the many bush cowpeas in circulation and unrelated to the climbing forms developed in Asia. I may try growing these again to hybridise with my best bush snake beans to see if I can introduce even more diversity and strength.

These remarkable little plants were put to the test this season, getting started in what has turned out to be a once in a generation drought (which sounds bad until you remember everyone goes through a few of these in a lifetime). They were sowed into barely improved clay that was dried to concrete, yet germinated in a week relying on nothing more than the residual humidity in the soil. They have now started producing pods a few weeks later despite the high temperatures, strong winds and meagre rain. The clay is still deeply cracked but the recent rise in humidity has put these plants into gear. The arrival of the monsoon in a week or two will see them hit full speed, churning out handfuls of crunchy pods for stews and stirfries every day. The magic and power in the garden is the ability to turn nothing into something and to fill an unmet need, and these little beauties have all that in spades.

Direct sowed and unirrigated snake bean seeds, planted in mid October and going strong ten days later.

The upright form with the long bed stretching into the distance. About 70 % of the spots planted got established.

The first mature pods from late December, air drying before more careful drying before storage.

The original superior form on the lower left, with the later upright form on the upper right. The difference is dramatic this season.