Known variously as corkscrew vine, corkscrew flower, or snail flower, Cochliasanthus caracalla (formerly known as Vigna caracalla) is a fast-growing, twining perennial vine with fragrant flowers, growing to as much as 30 feet in length. It is a perennial evergreen in frost-free regions (zones 9 to 11) but is often grown as an annual in zones 2 to 8. From July to October, and up until the first frost, the corkscrew vine blooms with highly fragrant white and lilac/purple flowers, sometimes marked with yellow and cream colors. Its spiraling flowers are about 2 inches long and grow in erect clusters, known as racemes, that can reach up to 1 foot long. Its vines sprout green leaves, which each have three leaflets about 3 to 5 inches long. The flowers are accompanied by dangling, narrow bean-like pods 6 to 7 inches long and 1 inch wide, containing round brown seeds.
This plant has invasive potential and sometimes aggressively self-seeds and naturalizes in warm regions, such as California. Once established, the corkscrew vine is a very fast grower and may very well take over your entire garden, and even the rest of your backyard, so be sure to closely monitor its growth and spread.
|Common Name||Corkscrew vine, corkscrew flower, snail vine|
|Botanical Name||Cochliasanthus caracalla or Vigna caracalla|
|Plant Type||Perennial vine (sometimes grown as an annual)|
|Mature Size||12-30 ft. tall, 3-6 ft. wide|
|Soil Type||Moist, well-drained|
|Soil pH||Acidic, neutral, alkaline|
|Bloom Time||Summer, fall|
|Flower Color||White, purple|
|Hardiness Zones||9-12 (USDA)|
|Native Area||South America, Central America|
Corkscrew Vine Plant Care
This member of the pea family is native to the tropical areas of Central and South America, and it thrives in regions that replicate these types of conditions. Ideally, give it full sun and moist, fertile, well-drained soil. It can be grown as a perennial in warmer climates, or as an annual in colder regions where winter temperatures dip below 40 degrees Fahrenheit.
The fast-growing corkscrew vine is relatively easy to grow from seed, however, its vine-like structure means it will need a support structure—a trellis, fence, or arbor—on which to grow.
This fast-growing perennial vine self-seeds readily and is widely regarded as an invasive plant in parts of California. Gardeners in any warm region may find it troublesome, likely to take over a garden unless closely monitored. Volunteer seedlings will need to be plucked from the garden to prevent spread of this plant.
Corkscrew vine will grow best when planted in full sunlight. It will tolerate partial sun, but will be somewhat sparser, with fewer flowers.
Grow corkscrew vine is soil that is fertile, moist, and well-drained. It tolerates a wide range of soil pH, from acidic to alkaline.
Soil should be consistently moist but never soggy. Water the vines only when they appear dry, by ground soaking rather than by overhead spraying. You should also allow the excess moisture to seep away after watering. Applying a 3-inch layer of mulch can help maintain soil moisture.
Temperature and Humidity
These plants love heat and humidity, and will always grow best in tropical climates. They will perform as evergreens in truly tropical environments, but may be semi-evergreen and die back in borderline regions that experience cold but not freezing winters. In regions where winter temperatures dip below 40 degrees Fahrenheit, they are likely to die out completely and will need to be treated as annuals.
Though the corkscrew vine doesn't necessarily require fertilizer, you can use an organically-sourced and balanced granular fertilizer, applied in spring, to promote its growth. Young plants will appreciate soil amended with compost and peat moss before planting.
Types of Corkscrew Vine
Some confusion exists because this plant has been categorized in several different genera over the years: Phaseolus caracalla, Vigna caracalla, and finally Cochliasanthus caracalla, now regarded by most sources as the most correct classification. You may, however, still find the plant categorized by any of these names at garden centers or in botanical literature. All three names, however, refer to the same plant.
In any case, you will find generally only one form of this plant offered for sale at garden centers and online retailers. There are no additional cultivars to choose from.
When a corkscrew vine first matures to full size in the spring and early summer, cut back the leaves and tendrils sharply to promote bushier growth and more flowers in late summer. This action will also help prevent the plant from overtaking your garden.
Propagating Corkscrew Vine
The corkscrew vine plant can be propagated by seed or by rooting softwood cuttings under high humidity, Here is how to propagate it through cuttings:
- In late summer, cut a 4- to 6-inch stem with plenty of leaves, using sharp pruners. Remove the leaves from the bottom half of the cutting.
- Dip the bottom of the cutting in powdered rooting hormone, then plant it in a small pot filled with a 50-50 blend of peat moss and perlite. Moisten thoroughly.
- Place the pot in a loosely secured plastic bag and place it in a bright window. In three or four weeks, the cutting should develop roots (tug on the cutting; if you feel resistance, it means the cutting has rooted).
- Move the plant outdoors and place it in a lightly shaded area. In the fall, transplant it into a suitable sunny spot.
How to Grow Corkscrew Vine From Seed
The corkscrew vine plant is easily propagated by seed and is usually started indoors, as it handles transplanting well. Seeds can be purchased or collected from the long seed pods that remain after the flowers fade. Try using toenail clippers to clip the seed coat (scarify it) at least halfway around the edge of the seed to encourage successful germination. Sow the seeds with only a light covering of soil on top. They will take up to six days to germinate, depending on the temperature of the soil and whether or not the seed coat is scarified.
This vine can aggressively self-seed, and it's also possible to simply transplant the volunteer seedlings that spring up in the garden to new locations.
Potting and Repotting Corkscrew Vine
In climates where corkscrew vine is not hardy, it is sometimes grown in containers and brought indoors for the winter. The pot can be of any material, provided it has excellent drainage. Any good quality potting mix makes a suitable growing medium. When grown indoors, it must get plenty of light, which can be hard to achieve during the winter months in colder climates; it will require the sunniest window you have. The corkscrew plant does not make a very good permanent houseplant—it needs to go outside during the warm summer months.
Rather than repotting when it outgrows the pot, it's generally easiest to simply discard it and plant new seeds of this fast-growing plant.
This is a tropical plant that won't survive frost, It is cold-sensitive and subject to chilling injury below 40 degrees Fahrenheit. In transitional zones (zone 9) it sometimes is semi-evergreen, dying back to the ground in winter. If this happens, simply cut the plant back to the ground; it will probably return the next spring.
If growing corkscrew vine as an annual, pull the entire plant from the ground when cold weather arrives, and plant new seeds or new nursery plants the following spring.
Common Pests & Plant Diseases
These plants are not associated with any significant insect or disease problems, but occasionally aphids may visit. Dislodge them by spraying the plants with water, or use a horticultural oil to control them.
Corkscrew vine is quite disease-resistant, but it may develop root rot if planted in poorly draining soil. Affected plants will need to be removed; amend soil to improve drainage before replanting.
How to Get Corkscrew Vine to Bloom
Under good circumstances (fertile, well-draining soil and a full sun location), corkscrew vine will produce beautiful and fragrant flowers from mid-July into October. The flowers bloom creamy white, then open to bright lavender to purple flowers. Deadheading spent flowers will lead to healthy growth and continued blossoming.
Lack of flowers is usually traced to a deficit of sunlight or poor soil fertility. A single feeding early in the spring is often all it takes to ensure ample blooming. Cutting back plants once as they are just maturing in late spring may prompt a heavier flush of flowers when the blossoms appear in midsummer.
Common Problems with Corkscrew Vine
The only problem with this plant is its extremely vigorous growth bordering on invasive. Make sure to shear or head it back severely to control its spread, and remove the spent flowers before they turn into seeds.
Is corkscrew vine the same as snail vine?
Yes. Some confusion arises because this plant has, at different times, been categorized as Phaseolus caracalla, then Vigna caracalla, and finally Cochliasanthus caracalla. But whether you know it as corkscrew vine or snail vine, it is the same species.
Where do the names "corkscrew vine" and "snail vine" come from?
The common name "corkscrew vine" derives from the way th showy flowers twist spirally on the vine. The name "snail vine" originated because the flowers curl up closely to resemble a mollusk shell.
How should I use this plant in the landscape?
In regions where it is winter hardy, use corkscrew vine to cover trellises, arbors, fences, or garden walls. In colder regions, you can grow it in containers and bring it indoors to a sunny window for winter.
Does corkscrew vine have wildlife appeal?
These plants, with their long bloom season, are known to attract both birds and butterflies.
Cochliasanthus caracalla. San Marcos Growers
Vigna caracalla. Missouri Botanical Garden.