With pink flowers and purple seed pods, purple hyacinth bean would not look out of place in a cottage garden. This Old World vine makes a beautiful landscape plant in the desert southwest. Learn how to start it from seed and take care of it.
Purple hyacinth bean (Lablab purpureus) is a charming annual vine prized for its beauty, not for its food value. While this plant has been grown traditionally for food and fodder, in the US it’s grown mainly as a decorative landscape plant and for its cut flowers.
Clusters of rosy pink flowers and burgundy-tinged green leaves make it an eye-catcher. Flowers are followed by leathery, magenta seed pods which contain 2 to 4 large seeds. The seeds are easy to save for growing more plants next year.
It blooms from summer through the first frost, providing bees, butterflies, and hummingbirds with a source of nectar.
Why I Like This Plant
- Easy to start from seed
- Grows fast
- Colorful flowers, leaves, and seed pods
- Low maintenance
- Attracts bees, butterflies, hummingbirds
Things to Watch Out For
Don’t let the word “bean” fool you. This “bean” is not edible. The seeds and pods contain cyanogenic glucoside and are considered toxic.
If you have a problem with deer and rabbits, this won’t be a good choice since they both relish this plant’s leaves.
Optimal Growing Conditions
If you’re thinking of growing purple hyacinth bean in your garden, you need to find a suitable place that will keep it healthy and looking good… while minimizing maintenance for you.
Here are the key factors to keep in mind.
Temperature
Purple hyacinth bean is native to Sub-Saharan Africa and India. It thrives in hot climates — both humid and dry. It doesn’t mind the heat of summer, even in Phoenix.
It grows as a tender perennial in USDA Hardiness Zones 10 – 11. If you grow it in Zone 9, treat it as an annual since it does not survive freezes.
Sun Exposure
Purple hyacinth bean can be grown in full sun to light shade, but plants are healthier and bloom most profusely when they get at least 6 hours of full sun.
Size and Growth Rate
Purple hyacinth bean is a fast-grower that quickly reaches a size of around 15 feet high and 3 to 6 feet wide.
Soil
Purple hyacinth bean’s preference is light, moist, neutral-to-acid, well-draining soil. It tolerates desert clay or sand, but doesn’t like the alkalinity. For this reason, you may want to plant it in an amended hole or grow it in a container.
Other Location Considerations
It’s a twining vine that readily grows up any nearby support structure such as a trellis, lattice, or fence to form a dense, if temporary, screen.
If left unsupported, it can be grown as an informal, sprawling ground cover to cover banks and slopes.
Plants do well in containers — a good option for those with alkaline soil or hungry rabbits.
Since the pods and seeds are toxic, keep plants away from curious children or pets.
Purple Hyacinth Bean:
The Essentials
| Common Name | Purple hyacinth bean |
| Scientific Name | Lablab purpureus |
| Origin | Sub-Saharan Africa, India |
| Plant Type | Annual vine |
| USDA Zones | Zones 10 – 11 |
| Cold Hardiness | To 32℉ |
| Flower Color | Purple |
| Flower Season | Summer, fall |
| Mature Size | 10-20′ high x 3-6’wide |
| Growth Rate | Fast |
| Sun Tolerance | Full sun, light shade |
| Water Needs | Moderate |
| Pests & Diseases | None |
| Cautions | Mildly toxic |
| Wildlife | Attracts hummingbirds, bees, butterflies |
How to Plant
Purple hyacinth bean is easy to grow from seed. (I’ve never seen this plant for sale at a garden center, only seeds.) The seeds are about the size of a kidney bean and have a distinctive white band.
Plant directly in a sunny spot after the danger of frost has passed. Seeds germinate best when planted in warm soil. Soaking seeds overnight greatly improves their germination rate. You can expect to see sprouts within 3 to 30 days.
How to Care for Purple Hyacinth Bean
Hyacinth bean vine doesn’t need much care.
Initially, new sprouts need to be kept moist. Plants become somewhat drought tolerant as they mature, but look their best when consistently watered.
Since it’s a nitrogen-fixing legume, it doesn’t need added nitrogen. However, since it’s non-native and a prolific bloomer, it can benefit from a monthly application of a low-nitrogen fertilizer, especially if grown in a pot or poor desert soil.
You can trim any errant branches or pinch the ends to encourage bushiness.
Plant Lover Facts
Purple hyacinth bean (Lablab purpureus) goes by other common names including hyacinth bean, Indian bean, and lablab.
It is the only member of the Lablab genus. The unusual name is derived from the Greek “lobos”, which means “pod.”
It has naturalized on all continents, but has not escaped cultivation in the US.
If you are a vegetable gardener, consider using purple hyacinth bean as a cover crop. A University of Arizona study on the use of cover crops, concluded that purple hyacinth bean makes an excellent summer cover crop for the low deserts of Arizona.
Thomas Jefferson, one of America’s earliest agronomists, is believed to have grown this vine, so seeds are sold by the Thomas Jefferson Foundation to support Monticello.
Edible or Toxic? (It’s Both)
Purple hyacinth bean has been cultivated in India for thousands of years. It’s grown for both food and animal fodder.
This plant has both edible and toxic parts, and toxicity depends on the dose and preparation. According to the North Carolina State Extension, it is only toxic if “large” quantities are eaten. Whatever “large” means. 🤔
The leaves and flowers can be eaten raw or cooked. The roots can be eaten cooked. The pods and seeds are toxic but can be made edible if boiled well with several changes of water.
I do not recommend trying this at home!
Have you grown this plant?
Was it a “hit” or a “miss” in your garden?
Please share your experience in the comments below!
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Author Bio
Deane Alban is the creator of Southwest Gardener. She is a science writer with a bachelor’s degree in botany from the University of South Florida. Gardening is her lifelong passion. She’s been gardening in Tucson for 15 years.
Photo Credits
Carolilna Lena Becker, CC BY-SA 3.0, via Wikimedia Commons
Steve Hurst, public domain, via Wikimedia Commons