Snail Vine, Slak-blom, Shell Vine, Corkscrew Vine, Caracalla Bean - Vigna caracalla

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Vigna caracallaVigna caracalla

You are unlikely to find this beautiful vine at a nursery, but may be lucky enough to have a friend who has one and can give you seeds. I have included it here for identification purposes as many old gardens still have it growing. Occasionally you can find seeds for sale on JunkMail, bidorbuy and other similar sites, as well as from speciality seed suppliers online. Petal Fair nursery list this plant  but it is often out of stock:  https://www.petalfaire.co.za

Condensed Version:

This fast growing fragrant vine is well worth trying to source for your garden, and will have your friends and family gasping with delight when they see it in full bloom. It can be difficult to obtain in South Africa, but seeds can be bought online, or if you’re lucky enough to have a friend with one, you could collect seed in autumn to sow next spring.

A great profusion of fragrant and unusually twisted flowers appear in midsummer and continue to autumn. The creamy-white blooms are beautifully shaded with primrose, shell-pink, lavender and golden tones; and in tropical regions this vigorous vine can climb 1 to 2 stories high in a single summer; with the blooms arising in 30cm long bunches, and dangling enticingly from anything they are allowed to scramble over. This evergreen vine thrives in high heat and humidity, and loves to grow in full sun (at least 6 hours a day).  It is tender to all but light frost and in cold regions will die down completely in winter; if the roots are thickly mulched it will often shoot again in spring; it can also be overwintered in pots. It is important to keep the soil moist but not sodden until the plant becomes established; thereafter allowing it to dry out slightly between watering. 

Full Version:

Description, History & Interesting Facts:

Vigna are members of the pea family and widespread in tropical regions of the world. There are about 160 species; 20 of which are native to southern Africa. The strange and lovely snailflower (Vigna caracalla) originates in tropical South America and Central America. Snailflowers are named for their blooms which resemble beautiful curled snail like shells.  A great profusion of these marvellously fragrant and unusually twisted flowers appear in midsummer and continue to autumn. The creamy-white blooms are beautifully shaded with primrose, shell-pink, lavender and golden tones; and in tropical regions this vigorous vine can climb 1 to 2 stories high in a single summer; with the blooms arising in 30cm long bunches, and dangling enticingly from anything they are allowed to scramble over.  The flowers are pollinated by ants attracted to the nectar and then produce long, slender, green bean pods which turn a golden brown when ripe. The attractive bright green foliage is evergreen in mild climates, with a soft, downy texture.

In 1792 Thomas Jefferson wrote about the Caracalla Bean saying "The most beautiful bean in the world is the caracalla bean which, though in England a green-house plant, will grow in the open air in Virginia and Carolina." Whether Jefferson ever received seeds or plants of this vine is not known, but the plant was already growing in gardens by the 1830’s, and documented in The American Flower Garden Directory. It was introduced into Europe in the eighteenth century.

In the Garden:

This fast growing fragrant vine is well worth trying to source for your garden, and will have your friends and family gasping with delight when they see it in full bloom. It can be difficult to obtain in South Africa, but seeds can be bought online, or, if you’re lucky enough to have a friend with one, you could collect seed in autumn to sow next spring.

It is magnificent twining up a tall pillar, arbor, archway, trellis, fence, or any other support; but be sure you position it close to a patio, entrance or window, where its heady fragrance can be enjoyed. Needless to say, it is essential in all romantic and perfumed gardens. In cold regions it would be wise to plant it in a large pot which can be moved to a protected position in winter; it even thrives in a large hanging basket. Allow it to twine up a trellis in the annual border behind cleome and cosmos; or pair it up with bold blooms like zinnias, marigolds, or petunias for a beautiful summer show.

Cultivation:

This vigorous evergreen perennial vine thrives in high heat and humidity, twining itself around any support it can find; and in ideal conditions will quickly reach 6m or more. It loves to grow in full sun (at least 6 hours a day).  It is tender to all but very light frost and in cold regions will die down completely in winter; if the roots are thickly mulched it will often shoot again in spring. In these regions it is often treated as a summer annual or planted in containers which can be overwintered indoors. Plant in deep, rich but well drained soil and it is important to keep the soil moist but not sodden until the plant becomes established; thereafter allowing the soil to dry out slightly between watering.  Placing a thick layer of organic mulch around the plant will help the soil to retain moisture as well as control weed growth.

Propagation:

The seeds, which are technically beans are nice and large and can easily be sown directly into garden beds in spring when the soil is nice and warm; and in cold regions once all danger of frost is over.  Pour boiling water over the seeds and let them soak overnight before sowing. It is more convenient to sow them individually into small pots, rather than seedling trays; thereby avoiding having to transplant them. To avoid root disturbance, plant the small vines into the garden or their permanent pots while they are still quite young. As your vine grows, keep it well watered and fertilise ever 4 weeks. You may notice that the plant grows very slowly until early to midsummer, before suddenly ‘taking off’ when the hottest weather arrives.

Pests & Diseases:

The snail vine is not troubled by any serious pests or diseases.

Additional Info

  • Common Name: Snail Vine, Slak-blom, Shell Vine, Corkscrew Vine, Caracalla Bean
  • Latin Name: Vigna caracalla