Black-eyed Susan vine, whose botanical name is Thunbergia alata, is a tender, evergreen, herbaceous perennial plant, but grown mostly as an annual. The plant is ideal for hanging baskets and containers.
Thunbergia alata is pronounced as [thun-BER-jee-uh] [a-LAY-tuh].
Common names of the black-eyed Susan vine include:
- Clock vine
- Bright eyes
The vine is native to tropical East Africa and belongs to the Acanthaceae family. One distinctive feature of the black-eyed Susan vine is its bright green, hairy and abrasive leaves.
Depending on the variety, the black eyed susan vine boasts of beautiful red, salmon, orange, ivory, yellow, pinkish, or white flowers.
Varieties of black-eyed Susan vines include:
- Canary Eyes
- Orange Wonder
- Angel Wings
The heart or arrow-shaped leaves on this flowering vine grow opposite to one another. The five petals surround a dark brownish-maroon center that imitates the shape of a disk.
This dark brownish-maroon disk-shaped center gives the plant its name, black-eyed Susan vine.
NOTE: The Black Eyed Susan plant (Rudbeckia hirta) is different than the vine.
Size & Growth
In USDA hardiness zones 10 and 11, black-eyed Susan vines remain a perennial plant. They are fast growing and flower fast. It is best grown as an annual decorative plant in cooler zones (USDA hardiness zones 3 to 9).
The plant is considered invasive in Cuba, Japan, Brazil, Australia, and other areas.
When grown in containers or temperate regions, this plant can grow up to eight feet. In frost-free zones, the black-eyed Susan vine can grow up to 20′ feet tall.
Black-eyed Susan vines grow well when provided with structural support though it can work well as a ground cover.
Try growing these plants alongside other vines like the purple hyacinth bean or the morning glory.
The orange, red, pink, white, and yellow colors on the black-eyed Susan vine will contrast nicely with the colors on these other vines.
Flowering and Fragrance
The black-eyed susan vine blooms from the middle of summer until fall frost.
Expect a pleasing display in late summer. Deadheading is not necessary to keep the flowers in bloom.
Light & Temperature
These plants require warm temperatures, and they do best when planted in full sun.
The black-eyed Susan vine can endure some shade, but flowering might reduce.
When exposed to enough sun, and as long as the temperature does not fall below 60° degrees Fahrenheit, the plant continues blooming.
However, in areas of dry or hot climates, it is advisable to grow the plants under some afternoon shade because the plant does not perform well when exposed to intense heat.
Watering and Feeding
The plants do not respond well to soggy soil, but neither do they to drought.
Mulch to maintain soil moisture at a moderate level.
For annual plants, shredded leaves or organic mulch works best. Such mulch provides the bed with a natural look and enriches the soil.
The plants require regular and deep watering throughout the growing season. Soil should remain moist but not wet.
Plants grown in containers should never be allowed to dry out.
In the blooming stage, fertilize every two to three weeks while avoiding over-fertilization.
Applying too much fertilizer can lead to excessive growth with fewer flowers.
Soil & Transplanting
The Black-eyed Susan vine requires a soil pH of slightly acidic to slightly alkaline.
The soil also needs to remain fertile and well-drained. However, if the soil is too dry, the plant will wilt.
Adding compost to the soil provides the ground with the much-needed nutrients.
Compost also helps with achieving the idyllic pH level that these plants appreciate.
If grown in a hanging basket, it is recommendable to use top-ranked potting soil.
Before transplanting in the garden:
- Ensure the temperatures have warmed up
- Choose a place in full sun
- Select a location with well-drained soil
Grooming and Maintenance
Thunbergia alata is a low-maintenance plant. Water well, deadhead, and give the twining vine a trellis is an effective way of grooming.
In zones where the plant grows as a perennial, pruning lightly is recommended.
Using plant ties on young plants is also useful, as it helps them create a growing structure.
How to Propagate Black-Eyed Susan Vine
Thunbergia alata plants grow from seeds, but cuttings work efficiently too. Propagating the plant from seeds helps it become vigorous.
Plants can be planted directly in the garden after the last frost passes.
It is recommendable to start seeds indoors (in peat pots if possible) for about 6 to 8 weeks before the frost clears.
Seeds usually take a long time to germinate, but the process can speed up when soaked in warm water. They should not take more than 21 days.
Conceal seeds completely by pressing them into the soil.
Propagating by Cuttings
- Use a stem of about 6″ to 8″ inches
- The stem should come from a tender, growing tip
- Put the stem in water
Propagating by Layering
Thunbergia alata can also be propagated by “layering.” To do this:
- Look for a vine growing close to the ground and bend it downwards.
- Measure 8″ inches from where the vine ends and cover it with soil
- Tie up the vine to prevent it from being destroyed by the wind
- Ensure the area in contact with the soil remains moist by watering
- After the roots develop, use the vine just before them for replanting.
Black-Eyed Susan Vine Pests or Diseases
These plants, especially those grown outside, are not prone to many pests and diseases.
As long as the plants receive enough water, sun, and air circulation, they should perform well.
When grown as an indoor plant, the black-eyed Susan vine is prone to plant scale, whiteflies, and spider mites.
This is a significant problem in areas with hot weather. Insecticidal soap can quickly fix the issues.
Keep on the look out for stem and leaf damage a sign of pests and diseases.
Also, black-eyed Susan vines grown indoors, where the heat is dry, do not thrive.