Ruby Moon hyacinth bean: let this vine twine

Dolichos lablab Ruby Moon Plant Select

When flowering vines are mentioned, many gardeners first think of Clematis. Climbing roses may enter the picture. It can take many years for either of these to achieve their full glory, but what if you could have a flowering vine that made a huge impact the first year?

Hyacinth bean in its brilliant purple cultivar ‘Ruby Moon’ is a vigorous vining cousin to beans with dark purple stained foliage attractive in its own right. The generous clusters of blue and amethyst flowers resemble a delicate wisteria, only these are produced abundantly from midsummer to the frosty days of autumn. By August expect this to be a focal point in your garden: hundreds of flowers produced together with huge flat purple bean pods and colorful foliage into the bargain.

This vine has become a focal point wherever planted at Denver Botanic Gardens: you too will soon find it to be an essential addition to a wall, fence in your garden or mounded upon itself as a perennial in the border.

View the plant profile here.



Ruby Moon Hyacinth Bean (Dolichos lablab ‘Ruby Moon’)

Annual vine
Height: 6-8′ trellised
Width: 3-5′ untrellised
Blooms: Late spring to frost
Sun: Full sun to partial shade
Water: Moderate
Hardiness: USDA zones 7 and warmer; annual elsewhere
Culture: Loam is best

Thanks to Panayoti Kelaidis, Denver Botanic Gardens, for writing this piece.

24 responses to “Ruby Moon hyacinth bean: let this vine twine”

  1. Sue Mahoney says:

    My horse often wanders the yard and samples plants. I saw recommendations to boil twice before eating. This lead me to wonder if this would be safe around horses. If you have any insight, please let me know. Thank you. Sue Mahoney

    • Ross Shrigley says:

      The beans of this plant are safe for humans to eat and are commonly used in dishes in India. Your horse should be ok eating these colorful beans and if your horse eats the plants of sweet peas, it’s probably ok to eat the rest of this plant too.

  2. Bitz says:

    I was given to understand this plant was an annual and yet you say it can be “mound upon itself as a perennial in the border”. Is it only an annual if you train it to climb? My cousin gave me some seeds and I can’t wait to see them grown. I was thinking of planting some in a half whiskey barrel and giving them a tomato cage to climb. However, from descriptions I’ve read, the cage wouldn’t be nearly tall enough. Is it OK to let the top flop over and twine around itself on the tomato cage? I don’t want to mess this up… cousin has a vivid green thumb and I don’t want to let her trust in me go to waste.

    • Ross Shrigley says:

      Unfortunately, this is only an annual climbing or not. There will be a better opportunity for flower pollination if it is allowed to climb and present itself to pollinators. Then the bountiful seeds will cover the ground and germinate for the next year. The seed pods are edible if you choose to harvest them for dinner instead of letting them fall to the ground.

  3. Beth says:

    I grow pole beans and have learned not to grow more than one variety if I want to save seeds because the hybridize. Will this ornamental bean do that with my edibles?

    • Ross Shrigley says:

      You should be safe. These are two different species of plants and should not successfully cross-pollinate.

  4. JoAnne Fanganello says:

    I would like to buy Hyacinth Bean, Ruby Moon. Could I purchase this at the Botanic Gardens? Thank you for your help. JoAnne Fanganello

  5. Becky says:

    Well, you can achieve this if you grow the Hyacinth Bean. (Dolichos lablab) The Hyacinth Bean Ruby Moon is a brilliant purple vigorous vine. The generous clusters of blue and amethyst flowers resemble a delicate wisteria or resemble sweet peas without the scent. In August, you expect this to be a focal point in your garden. Hundreds of flowers are produced together with huge flat purple bean pods and colorful foliage.

  6. can I direct sow into the ground or should they be started indoors or cold frame

    • Ross Shrigley says:

      These can be sown directly into the soil after the last frost. Enjoy! The beans are edible too.

      • Ruth says:

        In fact, they prefer to be direct sown, I think. I had started mine indoors and when I transplanted them, they really struggled, but finally took off like banshees! Read somewhere that they don’t appreciate transplanting…. so this year they go directly in the ground. I harvested A ZILLION seeds from last year’s growth – a bonus!

  7. Sherry Sommer says:

    I love to train green beans and scarlet tuner beans on trellises but they have been covered with Japanese Beetles the past few years.

    Would the Ruby Moon bean attract JB’s as well?

    • Ross Shrigley says:

      I’m not sure, but probably.

      • Ruth says:

        Mine did not. It’s a gorgeous plant that was visited frequently by hummingbirds. In my region (zone 6A) Jap beetles are abundant in July – this plant doesn’t flower until end of summer, and there was no problem whatsoever

  8. Started my ruby moons inside on a sunny window on 4/6/21. They did great. I pinched them back to encourage branching and they are happy. Finally warm enough to plant outside, but will harden them off first. We are 9n zone 5b in Southern New Hampshire. Happy Gardening to you all!

  9. Judith says:

    Helo! I have a Ruby Moon plant. At first I had lovely flower. Now I just have purple pods. Will I have more flowers?

    • Ross Shrigley says:

      It may have occasional flowers, but no the bean pods are the show now and/or you can cook them and eat them.

  10. Debbie says:

    I am planting Ruby Moon and Silver Moon in a large pot with a tall trellis. Will they cross pollinate and if so, what do you end up with? Thank you

    i have had really good luck potting the Ruby Moon in pots with a tall trellis in the past. This is my first time mixing in the Silver Moon

    • Ross Shrigley-Plant Select says:

      They theoretically can cross, if they do and something unique pops up next year, please let me know! Enjoy!

  11. Susie Blair says:

    Will they climb up a fence or do you need a trellis?

    • Ross Shrigley-Plant Select says:

      They will climb a chain-link fence as high as tall as the fence goes. If it’s a wood fence, you’ll need to staple some string lines up to the top. Enjoy this ornamental-edible plant!

  12. Peggy Barnaba says:

    How do you know when the pods are mature to take the seeds?

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