How Do I Grow Sword Beans?

Or more importantly, what are sword beans?

Think of sword beans (Canavalia gladiata) as haricot bean alternative. Both are vines and sword bean needs  a garden in a frost-free climate to grow really well.

Fancy something different for dinner?

I grow sword beans in a sunny spot in compost rich, freely draining soil. I train them on discarded fishing net attached to a sturdy bamboo wigwam. I have also grown them over  archways. The key things are: 1 to provide a sturdy support, 2 to harvest what you grow and – most importantly – 3 site your plant well within your property boundary. They crop at the tips and picking is impossible if they end up next door!

Sword bean is a short-lived tropical perennial vine. It’s sometimes described as being an under-exploited food crop. Sword beans can grow 4-7m high in one season, but they are not invasive. They can be cut back hard in autumn, but plants often die in winter. The truth is they’re not reliably perennial, even in the frost free subtropics, and since they crop best in their first year I recommend growing them as an annual, sowing them in mid-spring.

In my garden sword bean flowers are pollinated by blue-banded bees. Large pods, 30-45cm long, are produced towards the end of summer and the seed gradually swell for several weeks (they fatten much more slowly than peas). It requires practice to identify when they’re fully matured, otherwise you don’t get much food from a pod.

Fresh sword bean seed must be peeled and then boiled, or added to casseroles. Peeling removes their outer skin which contains toxins. These toxins aren’t potent, but can cause nausea if you over indulge yourself. Once seed has dried, it cannot be peeled and so cannot be detoxified. Save your best dried seed for sowing next year.

Sword beans don’t have any serious pest or disease problems in Australia, but aphids may spoil flowers (reducing yield), grasshoppers tend to nibble their leaves, and leaf-cutter bees (which help pollinate sword bean flowers) sometimes use leaf pieces for making egg laying tubes.

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Jerry Coleby-Williams

10th August 2012