Description and Overview:
Thunbergia alata, or Black-eyed Susan vine, is a frequent sight in hanging baskets at the garden center. As common as they are, most people not only don’t know what they are, they don’t think to grow them. That’s a shame, because Black-eyed Susan vine is as easy care as it is charming. The flowers have an almost pop art look to them, with a solid center surrounded by a ring of clear colored petals.
Leaves: The medium green leaves are a little coarse and grow opposite one another. They can be either heart-shaped or a kind of lanced arrowhead shape.
Flowers: The flowers look daisy-like at a distance, but they are actually tubular. Five overlapping petals surround a brownish-purple center tube, masquerading as a center disk. Look at the flower from the side and you’ll see how the center funnels downward.
Flowers are most commonly found in orange, pale yellow or white, but new cultivars are being created with a wider color palette.
Thunbergia alata (Pronounced thun-BER-jee-a ah-LAY-tah)
Black-Eyed Susan Vine
USDA Hardiness Zones 9 – 10. Thunbergia alata is usually grown as an annual, although it has been known to over-winter in cooler climates, during very mild winters.
You will get the most flowers and the healthiest plants if you plant your Black-eyed Susan vines in full sun.
In hot climates, growing the plants in partial afternoon shade is recommended.
In good growing conditions, they can reach 6 – 8 ft. (h) x 12 – 36 inches (w) Mature size depends on variety and growing conditions. Plants grown as annuals may not reach mature size.
Black-eyed Susan vine repeats blooms from May through Fall.
If you are purchasing plants, you may only find them labeled as “Orange” or “Yellow”. There are more varieties offered from seed.
“Angel Wings” – White flowers with a hint of fragrance
“African Sunset” – Burgundy centers surrounded by red, ivory and darker shades of apricot and salmon
“Spanish Eyes” – Unusual pastel shades of peach and apricot
“Superstar Orange” – Traditional orange petals and dark center
“Susie Mix” Flowers in yellow, orange and white
Thunbergia grandiflora – Blue Trumpet Vine, Skyflower – Violet-blue trumpet shaped flowers with yellow throats
Thunbergia gregorii – Orange Clock Vine, Orange Trumpet Vine – Brilliant golden-orange trumpet-shaped flowers
Black-eyed Susan vines grow quickly, once the temperature warms up. They will tangle themselves around the nearest support or spill over edges. They are perfect for hanging containers, but flow just as easily over walls and raised beds.
A lattice or link fence makes a good choice for coaxing and weaving your vine into a living wall, but these plants will clamber over just about anything, from the mail box to an old tree stump.
With their quick growth habit and sprawling nature, Black-eyed Susan vines can overtake nearby plants and are often grown as solo performers.
However a nice option is to mix the Black-eyed Susan vines with another vine that will intertwine with them. Morning Glories are often used for this purpose, particularly the purple varieties, which make a nice color combo. Purple Hyacinth bean is another good choice.
They look beautiful near shorter purple flowers, like salvia and veronica, too. On the flip side, you can play up their flair with hotter colors, like brilliant red zinnias or canna, for a more tropical look.
Soil: Black-eyed Susan vine likes a fairly neural soil pH, of around 6.5 and a soil rich in organic matter. When setting out plants, work several inches of compost into the soil, if it is not sufficiently rich to start with.
Planting: Container grown plants are fairly easy to find, but Black-eyed Susan vine is easy to grow from seed.
[Seeds may seem relatively expensive, but that’s because the seed is difficult to collect.] You can start seed indoors, about 6 – 8 weeks before your last frost date, or direct seed outdoors after danger of frost. Soak the large, hard seeds in water for a day or two, before planting.
Black-eyed Susan vine plants don’t like having their roots disturbed and it helps if you start the seed in peat or paper pots. Plant the seeds about 1/4 – inch deep and expect them to germinate within 2-3 weeks, depending on the temperature.
Black-eyed Susan vine is quick growing and repeat blooms throughout the summer. That means they will get hungry and will need a light feeding every 4 – 6 weeks, with a complete fertilizer, to keep it growing strong.
Although the vines don’t like sitting in wet soil, they also don’t like being hot and dry. Mulching around the base of the plants will keep the roots cool and moist, without fear of rotting.
Since Black-eyed Susan vines are perennial, you can pot up a plant and bring it indoors for the winter. You’ll probably want to cut it back to a more manageable size when you do. You can also take stem cuttings and make new seedlings. If you’d like to try your hand at saving seeds, Mr. Brownthumb has a nice tutorial.
Pests & Problems:
Black-eyed Susan vine is not prone to many problems, particularly if the vines are kept healthy and have plenty of sun, water and air circulation. Whiteflies and spider mites can be potential problems, especially during hot weather and if brought indoors with dry heat. Keep a keen eye, to catch and treat any outbreaks quickly with insecticidal soap.