Climbing shell plant (Vigna caracalla), also known as snail vine or corkscrew flower, derives its common names from its twisting growth habit and ornamental blossoms that appear similar to snail shells. The plant's fragrant, colorful flowers occur in shades of white or cream with pink to lilac markings and contrast against the medium-green foliage. Hardy in USDA zones 9 through 10, climbing shell plants cannot tolerate cold temperatures and make suitable garden plantings for only the warmest areas of the country. Gardeners in the southern-most United States grow the vine outdoors on trellises, fences and arbors. Most American gardeners, however, grow the plants indoors to better control their growing environment.
Plant climbing shell plants in a location that receives six to eight hours of full sunlight throughout the day. Maintain a temperature of 60 to 85 degrees Fahrenheit at all times for optimal growth. Never expose to temperatures below 40 degrees to avoid cold damage.
Provide an inch of water per week to climbing shell plants, which keeps the soil from drying out completely. Decrease the watering frequency to once every two weeks during winter, when the plant is dormant and needs less moisture to survive.
Feed climbing shell plants once every two to three months using a balanced 10-10-10 NPK fertilizer. Check the instructions provided by the manufacturer for proper application and dosage. Water lightly after applying, soaking the soil to a depth of about 1 inch, to prevent root injury.
Prune the vine during any time of year to keep it growing in bounds and improve aesthetic appeal. Remove any dead, damaged or diseased growth, and cut back excessively long stems to maintain a compact growth habit.
Re-pot climbing shell plants once every two to three years during early spring, just before the onset of new growth. Increase the size of the container by at least 3 inches to provide plenty of room for additional root growth. Use a fresh growing medium of well-drained, moist potting soil to ease the transition.