Black-eyed Susan Vine, Thunbergia alata

Thunbergia alata is a fast-growing, free-flowering vine.

Thunbergia alata is a fast-growing, free-flowering vine.

Black-eyed Susan vine is commonly grown in the Midwest as a season annual to provide color in a vertical setting. This plant, Thunbergia alata, is actually a tender evergreen perennial in the acanthus family (Acanthaceae) native from tropical East Africa to eastern South Africa that is hardy only in zone 9 and 10 (and is completely unrelated to Rudbeckia hirta, an herbaceous annual or short-lived perennial in the daisy family (Compositae) native to north America also commonly called black-eyed Susan). But because it grows and flowers relatively quickly it is often used as an annual ornamental garden plant in cooler areas. It should be used with caution in frost-free areas as it has become invasive in many warm locations throughout the world.

This trailing or twining vine grows rapidly from seeds, reaching up to 8 feet in a single season under ideal conditions, but more often only 3 to 5 feet in the

This vine grows by twisting around supports (L) and had heart-shaped, softly hairy leaves (R).

This vine grows by twisting around supports (L) and has heart-shaped, softly hairy leaves (R).

Midwest (and much more in frost free climates). The plant is a rambler, climbing by twining (growing in a spiral up a support) rather than by clinging or producing tendrils as some other vines do. The opposite, oval to triangular or heart-shaped leaves grow up to 3 inches long on winged petioles. They are soft and hairy, dull dark green on the upper surface and pale green with prominent veins below, with slightly toothed margins.

Showy flowers in shades of orange and yellow are produced singly in the leaf axils. Each 1½ inch wide flower emerges from a small yellow-green calyx enclosed in 2 large, ridged, hairy, green bracts. The trumpet-shaped corolla opens flat with five overlapping petals surrounding the brownish-maroon center.

Showy flowers (RC, from side and R from front) emerge (LC) from hairy bracts (L).

Showy flowers (RC, from side and R from front) emerge (LC) from hairy bracts (L).

Pollinated flowers develop a fruit (LC) enclosed in the green bracts (L), which ripens and dries (RC) to a tan color.

Pollinated flowers develop a fruit (LC) enclosed in the green bracts (L), which ripens and dries (RC) to a tan color.

Plants bloom from mid-summer to frost, often with the best display in late summer. The species typically has brilliant orange flowers, but there are cultivars in pastels and white as well. Butterflies, bees and hummingbirds will visit the flowers.

Each fruit releases a number of reticulate seeds.

Each fruit releases a number of reticulate seeds.

Seeds are often produced late in the season. The fruit resembles a bird’s head with a round base and a long ‘beak’. Each fruit contains 2 or 4 semicircular, reticulate seeds.

Black-eyed Susan vine will quickly cover small structures.

Black-eyed Susan vine will quickly cover small structures.

Black-eyed Susan vine does best when allowed to grow on some sort of support structure instead of just rambling through adjacent plants, although it can be used as a ground cover. It makes a dramatic focal point when grown on a tall tuteur or other decorative support in a border or bed, will cover a fence, arbor or trellis along a wall for decoration or to create a quick privacy screen, and will

This vine will cascade down walls or from hanging baskets in addition to climbing.

This vine will cascade down walls or from hanging baskets in addition to climbing.

cascade from a hanging basket (as well as grow up the hangers). Try combining black-eyed Susan vine with other aggressive vines such as morning glory or purple hyacinth bean. The orange or yellow flowers would contrast nicely with purple or blue flowers, such as salvia or ageratum, or purple-foliaged plants (such as Persian shield or purple heart) planted adjacent to the vine’s trellis. Use hot-colored flowers such as tall red zinnias, orange marigolds, or bright yellow celosia for a completely different look.

Cultivars offer different colors than orange.

Cultivars offer different colors than orange.

Or combine them with bright red cannas and large elephant ears for a tropical look.

White, orange and yellow Thunbergia alata in a large container.

White, orange and yellow Thunbergia alata in a large container.

This vine can be used in a large container with a small trellis, and can be grown as an indoor plant (although it will likely need to be trained and pruned to keep it at a manageable size). Plants in containers will bloom over winter if kept in a sunny place and night temperatures are above 60 degrees.

In frost-free climates this vine is perennial and will grow very dense.

In frost-free climates this vine is perennial and will grow very dense.

The vine will quickly fill narrow vertical spaces with color.

The vine will quickly fill narrow vertical spaces with color.

Thunbergia alata grows best in rich, moist soil in full sun. It tolerates partial shade but flowering may be reduced. Seed can be sown directly where the plants are to be grown once soil temperature reaches 60F in the spring, but transplants give better results in the short growing season of the upper Midwest. Plant near the trellis, fence, or other support structure, 14-16” apart. Fertilize every 2 to 3 weeks when in bloom if grown in containers. Outdoors blackeyed Susan vine has few pest problems, but if grown indoors it is readily infested by spider mites and whiteflies.

Black-eyed Susan vine is most often propagated from seed.

Black-eyed Susan vine is most often propagated from seed.

This plant is most commonly propagated from seed (although softwood cuttings can be taken or stems layered, too, but plants grown from seed tend to be more vigorous). Start seeds indoors 6 to 8 weeks before the average last frost, and plant outside once all danger of frost has passed and night temperatures remain above 50F. Soaking the seeds in warm water overnight before sowing will speed germination. Press the seeds into the soil, covering completely. Seeds should germinate in 10-21 days. Plants grown in containers can be overwintered indoors in a warm, very bright room.

There are many different.cultivars available.

There are many different.cultivars available.

Often just the basic orange type is offered for sale as plants or seeds, but there are many cultivars. Some of the more common or interesting ones available include:

  • ‘African Sunset’ – includes shades from cream to brick red
  • ‘Arizona Dark Red’ – has intense deep orange-red flowers
  • ‘Blushing Susie’ – is a mix in shades of apricot and rose and dark centers
  • ‘Bright Eyes’ – has all white flowers
  • ‘Canary Eyes’ – offers yellow flowers with a dark center
  • Lemon A-Peel™ – has bright yellow flowers with a very dark center
  • Orange A-Peel® – PP14767 has bright orange flowers
  • ‘Orange Wonder’ – all bright orange without the dark center
  • A yellow cultivar.

    A yellow cultivar.

    ‘Pure White’ – all white flowers

  • ‘Raspberry Smoothie’ – has pale lilac-pink flowers and more grey-green foliage
  • ‘Spanish Eyes’ – is a mixture of flower colors in more muted shades of apricot, terra cotta, salmon, rose and ivory, all with a dark center
  • ‘Superstar Orange’ – has extra large, bright orange flowers
  • ‘Susie’ mix – includes orange, yellow and white flowers with or without contrasting dark eyes

– Susan Mahr, University of Wisconsin – Madison


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17 comments

  1. Hi! I have 2 black eyed Susan vines and want to bring them in for the winter. How much do I cut back to overwintering? And will they come back? A lot of my vines broke off trying to untangle them to bring in. Will they come back?

  2. I got a Raspberry Smoothie thunbergia this spring to grow in one of the village flower beds. It has overtaken the bicycle that I ‘planted’ it neara and is the focal point of the garden. I will collect seeds in hopes that I can get several plants for the other gardens.

  3. I bought my first Blackeyed Susan Vine at the farmers market in May. I feel in love with the flower and had to have it. It has now outgrown the first two trellis I have bout, it now stands at about 8 feet tall and does not seem to be stopping. It is absolutely beautiful, but my husband and I don’t know quit what to do with it. We live in an apartment and it is planted in a flower box. I would also like to know when I should winterize it and how to winterize it. I would also like to know if there is a way to tame or slow it down? We live in Portland Oregon.

  4. I am working on a project and I need to know – how deep should the pot be at the minimum? And do the have a big root system or a small root system?

  5. Can anyone tell me how to take softwood cuttings from the plant to grow more? I’m not too sure on what softwood would be considered.

    • Cut it about 8 inches from the tip of one Vine. Soak it in a vase of water until you see the roots on it. Then it’s ready to plant. Good luck

  6. Ok just bought my first two black eyed Susan’s. I live in Florida. Can someone tell me how to collect seeds from my own plants. I adore this plant? They are growing in hanging baskets. Now I am trying to figure out how to put them into a larger container. Any suggestions?

    • This is Known to be the Hardest Plant To Get Seeds off. I can tell you that after the Flower Blooms there is a Brown Pod known to look like a Birds Beak . Inside the Round End (only)
      You will find 2-3 Seeds. When you are collecting Seeds it’s best to Always have a Napkin Or something Under Where you are picking the seeds from . So you don’t drop and lose any You might be lucky enough to find. Good luck

  7. There is certainly a ripple effect that happens and it will spread to other neighbors. It’s not hard to inspire others and this is a great way. Thank you for such a good post.

  8. I am looking for the Pink Thunbergia Seed. I can’t seem to find it anywhere. I’ve researched on the and have contacted some seed company’s. Does anyone know where to order Thumbergia ‘Raspberry Smoothie’ or know of a pink variety? Thank you.

    • Marion says:
      This year I purchased the first “pink/mauve” Thunbergia plant from the Vite Nursery in Niles, Michigan.
      Previously I always purchased the yellow with black centers. My experience was that the pink didn’t
      flower as much. That’s why I was not able to gather seeds. But I will try again next spring. Vite has a
      great online website. Hope you look into it.
      Good luck to you!

  9. I did not realize that this vine can become invasive in many warm locations throughout the world. I usually use this vine in my gardens and grow on a 5 foot free standing trellis. I have only seen the yellow and orange cultivars. I would love to find some of the others.

  10. My thunbergias are blooming less than in years past although planted in the same spots. I use new dirt in the containers each year, slow release fertilizer and some composted manure. Any ideas on what fertilizer combination I might try to boost the blooming?

    • Are you purchasing new plants each year or using seeds from existing plant? I grow thunbergia – mostly orange with dark eye, at my home in NC and at my summer home in Maine. I have been growing them for over 10 years I feel the plants I purchased in 2006 were more Hardy and showy(more blooms). I collect seeds each fall as well as purchase /grow the newer colors. In the spring, once plants are established, filling out, 18″ vines, I fertilize all flower bearing plants with bloom booster 9-59-8. IMO the recent plants are less showy and smaller at season end than they used to be. However, the plants I grew from seeds I collected seem to be more hardy and showy. The original yellow w/black eye and orange w/black eye produce far more seed pod than the newer colors(orange a-peel, Arizona/African sunsets, super star.) I have nothing to back up this theory except personal experience. Like you, I plant thunbergia in same locations each year as well as additional plants in new locations in my yards.
      They are lovely plants, my husband calls them “THE HAPPY PLANT “

    • I bought this plant in Michigan and really love it. It’s been blooming constantly in
      June, July and now August. Many of my friends love it but no flower business knows
      anything about it

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