Learn how to grow purple hyacinth bean vine, and add this vigorous ornamental vine to your garden. Beautiful purple flowers and striking pods add beauty and interest.
Grown as a perennial in zones 10-11, purple hyacinth bean vine loves the heat. In cooler zones, it is grown as an annual from seeds planted in the spring.
Originally from tropical India and China, these vigorous vines easily cover a fence or trellis, and the blooms are gorgeous in the fall. Also called “Jefferson Beans”, purple hyacinth bean vine was first planted at Monticello in 1804. It is still featured in Thomas Jefferson’s Monticello kitchen garden.
These few tips are all you need to learn how to grow purple hyacinth bean vine.
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5 Tips for How to Grow Purple Hyacinth Bean Vine
1. Plant purple hyacinth bean vine at the right time
Not a true bean but a member of the pea family, purple hyacinth bean vine does best seeded directly in the garden. Plant when temperatures warm in the spring and nights are above 50℉. Plant hyacinth bean seeds 1 inch deep and 6 inches apart. Soak seeds for 6-8 hours before planting to speed germination.
If the weather gets too cold, the plants will slow or stop growing until temperatures warm. In cooler climates, start seeds indoors (a few weeks before planting), but do not let plants get too large before planting outside.
In the low desert of Arizona, plant from the middle of March through the end of May.
2. Choose a sunny spot for purple hyacinth bean vine
While generally low maintenance, purple hyacinth bean vine requires moist, well-draining soil in a sunny location. When grown in partial sun, the vine is more susceptible to fungal diseases, and roots will rot in overly-wet soil.
Plants grown in full sun have more blooms and more vigorous vines. Otherwise the plants are relatively pest and disease free.
3. Give the vines something to climb
The roots of purple hyacinth bean vine are close to the surface and do not like to be disturbed; put trellises and supports in place at time of planting. Vines can climb up to 16 feet in only a few months. Just a few plants will cover a trellis, fence, or arbor. The vines may need some guidance finding the trellis, but once there, they will twine and wrap easily around, and up, and maybe back down again.
4. Be patient waiting for blooms to appear
The vigorous vines grow quickly, but flowers often wait until mid-summer to make an appearance. You’ll be rewarded for your patience with profuse bloom sprays on stalks growing out from the vines. Flower clusters resemble pea blossoms, and are followed by distinctive leathery-looking purple pods.
5. Harvest seeds to share and plant next year (but don’t eat them)
Although the purple hyacinth beans are consumed in several parts of the world, preparation is tricky (due to the toxic levels of cyanogenic glucoside). Leave the eating to experts, and save seeds at the end of the season to plant next year and share with friends.
You’ll know the seeds are ready to harvest when the pod changes from bright purple to silvery purple, and the beans are plump and firm.
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Cook the pod before eating them. Unripe pods are popular veggie dish in South Asia.