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How to Grow Hyacinth Bean Vines

Caren White is a Master Gardener and instructor at Home Gardeners School. She has been associated with Rutgers Gardens for over a decade.

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I have a vegetable garden in a community garden. Last year, someone planted hyacinth bean vines around the entrance to the garden. They had gorgeous flowers and deep purple pods. By the end of the summer the vines had grown at least 12 feet, making quite a statement when you entered the garden.

What are Hyacinth Bean Vines?

Hyacinth bean vines (Lablab purpureus) are a member of the bean family that are native to tropical Africa but have since spread throughout the tropics. In the US, they are hardy in zones 9 – 11. In the tropics, the vines are perennial, but in areas that are not tropical, they are grown as annuals.

Hyacinth bean vines grow so vigorously that they make an excellent screen for privacy.

Hyacinth bean vines grow so vigorously that they make an excellent screen for privacy.

The vines are quite long, growing 10 to 15 feet in a single season. They grow so rampantly that they make an excellent screen. The vines need support to grow on so you will need to provide them with a wire fence, trellis, tepee or strong netting. They climb by twining around their support so whatever you install, it will need to be something that the vines can twine around. For best results, gently guide the young vines to twine around the support. Once they have attached, they will grow vigorously with no further assistance on your part.

The flowers, which can be lavender or white, will appear any time from mid-summer to fall. Hummingbirds find them irresistible. The vines will flower continuously until frost. As each flower fades, it is replaced by a shiny purple pod. Hyacinth bean vines are often grown for their ornamental value thanks to their lovely flowers and colorful pods.

Hyacinth beans are poisonous.  If you want to eat them, you must boil them and change the water 2 to 3 times.

Hyacinth beans are poisonous. If you want to eat them, you must boil them and change the water 2 to 3 times.

Are Hyacinth Bean Vines Poisonous?

All parts of the vines are edible, even the roots. Only the beans are poisonous. You will need to exercise caution when eating them. The beans need to be boiled with 2 to 3 changes of water. They contain cyanogenic glycosides. When eaten, the stomach acids convert that to cyanide. Symptoms of poisoning are vomiting, convulsions and even coma. When the beans are boiled, the cyanogenic glycosides are leached from them which is why multiple changes of water are necessary to make sure that all of the poison has been removed.

How to Grow Hyacinth Bean Vines

Choose a sunny location in your garden. The vines prefer full sun. They will grow in partial shade but they won’t produce as many flowers and pods. They need rich, well-drained soil. They also like to be moist. Don’t let the soil dry out.

Because they are such vigorous growers, you will need to fertilize them monthly. Use a fertilizer that has a low first number (nitrogen) such as 5-10-10 or 5-10-5. The middle number is phosphorous needed for flower and fruit production.

I’m an organic gardener so I don’t use regular fertilizer. My preferred fertilizer is Organic Neptune’s Harvest made from fish and seaweed. Its formula is low in nitrogen and higher in phosphorous. I like it because I can use it on my flowers, vegetables, herbs and houseplants. It’s easy to use. It comes concentrated and you dilute it in the amount you need. I can make a small amount when I am fertilizing my houseplants or a larger amount when I am fertilizing my garlic in the spring.

Hyacinth bean vines are grown not just for their flowers, but also for their purple pods.

Hyacinth bean vines are grown not just for their flowers, but also for their purple pods.

How to Grow Hyacinth Bean Vines From Seed

Hyacinth bean vines are most often grown from seeds. You should install your trellis or other support system before planting your seeds or seedlings. Because they have hard coverings, the seeds should be soaked overnight before you plant them. I use what I call the cup and saucer method. I soak the beans in a teacup which I cover with its saucer to keep my curious cats (or curious children if you have them) out of them. Because I am usually soaking different kinds of seeds, I place the seed packet under the teacup so that I know which seed is in each cup.

You can direct sow the seeds in your garden in the spring when the night time temperatures are consistently warmer than 50⁰F. Plant the seeds 1 inch deep and 6 inches apart. Germination should occur in 7 to 10 days.

You can also start your seeds indoors 4 to 6 weeks before your last frost date. Plant the seeds 1 inch deep in a container filled with moist soil. Germination should occur in 7 to 10 days. You can transplant your seedlings outdoors in your garden when night time temperatures are consistently warmer than 50⁰F.

How to Harvest Hyacinth Beans

You can harvest the immature green pods to cook as you would green beans or you can wait until the pods turn the characteristic purple color and have filled out to harvest them. The seeds are usually dried and then stored in a well-sealed glass jar. When you are ready to cook the dried beans, remember to boil them and change the water 2 to 3 times to ensure that all of the cyanogenic glycosides have leached out so that they can be safely eaten.

© 2019 Caren White