With its fragrant lavender blooms, purplish leaves and fast, sprawling growth habit, hyacinth bean vine (Lablab purpureus) is a striking ornamental that can quickly provide a bold splash of summer color. When planted in a suitable site, the vine requires minimal maintenance and care to provide an abundance of its signature pea-like flowers.
Choose Sunny Site
A native of tropical Africa, hyacinth bean vine is a frost tender perennial that will survive winters in U.S. Department of Agriculture plant hardiness zones 10 and 11. In all other zones, the vine may be grown as an annual. Hyacinth bean vine needs full sunlight to thrive. Capable of growing up to 15 feet long, hyacinth bean vine also requires a sturdy structure such as an arbor, fence or trellis to support its bulk. If growing multiple vines, provide at least 12 inches of space between plants.
Plant in Well-Draining Soil
Hyacinth bean vine is not picky about soil and will tolerate dry, poor soils so long as adequate drainage exists. Best growth will occur in a rich soil enhanced with organic matter with a pH between 5.5 and 6. Though drought-tolerant, the vine can benefit from regular irrigation during warm, dry periods. Water when the top inch of soil feels dry to the touch. If the vine is grown in a greenhouse, the Royal Horticultural Society recommends misting the plant with water daily to raise humidity levels. Plants being overwintered in a greenhouse should be transitioned gently to the garden by being stored outside in a protected, sunny area for a few days.
Fertilize to Help Flowers
To aid flowering, fertilize every two weeks during the growing season with a potassium-based fertilizer such as a 0-0-25 fertilizer. Using a hand sprayer, apply 3 to 8 ounces of fertilizer per 1,000 square feet, covering foliage evenly. Fertilizer may be applied mixed with water. Wear protective clothing such as rubber gloves, long sleeves and pants when spraying the fertilizer.
Check for Beetles
Although insects generally don't cause serious problems for the vine, Japanese beetles can cause unattractive feeding damage on its foliage. Gardeners can easily identify Japanese beetles, a type of scarab beetle, by their metallic green and copper coloring. Throughout the growing season, handpick beetles and drown them in soapy water. You can also hang bait traps at least 50 feet away from the vine to capture and kill beetles. Traps must be emptied regularly to be effective as they may attract more beetles when poorly maintained.