Vine
Snail Vine
Cochliasanthus caracalla · Fabaceae (legume family)
Also called: Corkscrew Vine, Snail Flower, Snail Bean, Caracalla Bean
Snail Vine (Cochliasanthus caracalla) is a low-water vine well suited to Tucson and the low desert. It thrives in full sun to part shade.
Snail Vine at a glance
- Water use
- Low (established)
- Sun
- Full sun to part shade; in Tucson afternoon shade reduces summer leaf scorch.
- Mature size
- 15-20 ft H x 6-10 ft W (twining; freezes back and resprouts so effective size is smaller)
- Growth rate
- Fast (can grow 1 ft per day in warm weather)
- Bloom
- Pale lilac, mauve and cream; buds open white-green and age to pink/purple. Coiled, snail-shell-shaped flowers., Late spring through summer into fall (warm season)
- Cold hardiness
- Root-hardy to about 20-25°F (USDA zone 9-11); top growth tender, dies to ground in a Tucson freeze and resprouts in spring.
- Soil
- Well-drained soil; tolerates most desert soils including alkaline; appreciates organic matter and good drainage.
- Native range
- Tropical South America and Central America (naturalized in subtropical regions worldwide)
- Best used as
- Trellis/arbor screen, Fragrant ornamental cover for fences and patios, Pollinator and fragrance garden
- Wildlife
- Sweetly fragrant (hyacinth-like) flowers attract bees and other pollinators; a legume that hosts some sulphur/skipper butterfly larvae.
- Toxicity
- Not considered significantly toxic; like many ornamental legumes the raw seeds/pods are not intended for consumption. Keep pets from chewing pods.
How to grow Snail Vine in Tucson & the low desert
Watering
Water deeply 1-2 times per week through the warm growing season once established; reduce in winter when it is dormant. Newly planted vines need consistent moisture to establish.
Fertilizer & nutrients
Light feeder. As a nitrogen-fixing legume it needs little fertilizer; an application of balanced or low-nitrogen fertilizer in spring promotes bloom. Excess nitrogen yields foliage at the expense of flowers.
Pruning & care
Cut back hard in late winter after frost kills the top; it resprouts vigorously. Thin and shape during the growing season to control its rampant twining growth on a trellis.
Notes
The true fragrant snail vine is Cochliasanthus caracalla (syn. Vigna caracalla, Phaseolus caracalla). It is frequently confused in the trade with the non-fragrant, purple-flowered Phaseolus giganteus (Sigmoidotropis speciosa); buy a fragrant clone to get the real thing. Frost-tender in Tucson but reliably perennial from the root.
Sources: University of Arizona Cooperative Extension / CALS (Tucson low-desert vine references); Arizona State University (Christine Martin) Desert Landscape Plant database; Wikipedia/Kew taxonomic treatment (Cochliasanthus caracalla)