Phaseolus: Greenhouse Plants
T – tropical, minimum of 18°C (65°F)
Phaseolus caracalla is the Snail Plant from tropical America. At Wisley Gardens, I discovered one of these that had sat in its pot in a corner for years, rather anonymously as it had lost its label, doing nothing at all; every so often somebody would come by with some secateurs and cut what straggly growth it had made back. When a climber had to be replaced I planted the then unknown plant into a shallow border of peat-basedand within 18 months it had grown enormous and produced curious, highly scented snail-shaped pinkish-white flowers. After flowering it is best to prune the plant back to its somewhat swollen rootstock, leaving a few nodes on newish growth behind. After a rest during the winter when it should be kept on the dry side it will sprout afresh in spring; watch out for red spider mite.
I am delighted to see that seed is obtainable. Apparently Australians used to grow this plant a lot outside in the hotter parts of their country to cover their outside lavatories. With the disappearance of these structures in modern times the plant has almost been lost to cultivation in that country.