Named for its resemblance to the popular hardy garden flower black-eyed Susan (Rudbeckia spp.), the black-eyed Susan vine (Thunbergia alata) is instead a tender perennial climbing yet bushy vine that is normally grown as an annual. It is a great plant for containers and hanging baskets and is particularly beloved for its distinctive flowers in vivid orange, yellow, and other colors. The flowers have dark centers, like the other black-eyed Susans, and the vine blooms for many weeks in the summer and into fall.
Black-eyed Susan vine is a diminutive vine that grows to a maximum of about 8 feet in temperate zones or when grown in containers, although it can grow to 20 feet in frost-free zones, where the plant is evergreen. The leaves are arrow- or heart-shaped and up to 3 inches long. This vine climbs by winding its way up support structures rather than clinging with tendrils.
Also called clockvine, the black-eyed Susan vine is grown as an annual in USDA hardiness zones 3 to 9 but can be grown as a perennial in zones 10 and 11.
|Botanical Name||Thunbergia alata|
|Common Name||Black-Eyed Susan vine|
|Plant Type||Flowering vine, annual or perennial|
|Mature Size||3 to 8 ft. tall, 3 to 6 ft. wide|
|Sun Exposure||Full sun to part shade|
|Soil Type||Fertile, well-drained|
|Soil pH||6.5 to 7.5|
|Bloom Time||Summer (as an annual)|
|Flower Color||Orange, white, yellow, red, pink|
|Hardiness Zones||10 to 11 (USDA)|
|Native Area||East Africa|
Black-Eyed Susan Vine Care
Black-eyed Susan vines are usually planted as annuals in containers or hanging baskets with mixed plantings, but they can also be planted in the ground to cover trellises, arbors, fences, and other structures. The plant works well to cascade down over retaining walls, and it can also serve as a ground cover. Aesthetically, it presents very well when combined with plants that have purple leaves or flowers.
If propagating or growing from seed, it's best to provide vertical structure in the ground or pots, for the vines before they need them, preferably before planting, so you don't have to disrupt the young plants later. You can simply plant them near a fence (with a post or planks they can climb), stand up a cage structure, or erect a tripod, or a tall pole.
Black-eyed Susan vines can be particularly aggressive where they grow year-round. The vine is considered invasive in many tropical areas, including Hawaii and Mexico.
Grow these plants in full sun to part shade. Some afternoon shade is beneficial, especially in warmer climates, as the hottest sun's rays may be damaging.
Plant a black-eyed Susan vine in soil that is rich, fertile, and well-drained with medium moisture-retention properties. It prefers a soil pH that is close to neutral.
Water regularly and deeply to keep the soil moist but not wet. If the leaves begin to wilt, the soil is probably too dry and needs a bit more water. In containers, do not let the soil dry out completely.
Temperature and Humidity
The black-eyed Susan vine thrives in warm, humid climates, which explains why it is invasive in tropical areas. However, it will grow anywhere in its zone range, provided it gets enough water. It tends to flower best after the hottest days of the summer are over.
Feed the plants (indoors or outdoors) every two to three weeks during their bloom season. Follow the package directions, but in many cases, it's best to use a half-strength solution of fertilizer designed to boost blooming.
Black-Eyed Susan Vine Varieties
Cultivars of Thunbergia alata have very similar foliage and overall habits and are mostly distinguished by flower color.
- 'Angel Wings': White flowers
- 'African Sunset': Dark red-purple flowers
- 'Arizona Dark Red': Deep orange-red flowers
- 'Blushing Susie': Apricot and rose flowers
- 'Canary Eyes': Yellow flowers
- 'Lemon A-Peel': Bright yellow flowers with a very dark center
- 'Orange Wonder': Bright orange flowers with no dark center
- 'Raspberry Smoothie': Pale lilac-pink flowers and grey-green foliage
- 'Superstar Orange': Extra-large orange flowers
- 'Susie' mix: Orange, yellow, and white flowers with or without contrasting centers
Propagating Black-Eyed Susan Vines
Propagating this vine from stem cuttings is easy and it's usually best done over the winter.
- Take a cutting several inches from a terminal end of a healthy plant.
- Remove the bottom leaves of the cutting.
- Place the cutting in a glass of water to root.
- Change the water in the glass every two or so days.
- When the roots thicken, plant it in a well-draining pot in potting soil.
- Grow the plant until spring and then transplant outdoors after the threat of frost has passed.
How to Grow Black-Eyed Susan Vines From Seed
This vine is easily started from seeds sown directly in the garden after the last expected frost date (when the soil is at least 60 degrees Fahrenheit). In colder climates, nursery transplants are normally used; or, you can start them indoors six to eight weeks before the last frost. Germination occurs about 10 to 14 days after sowing in warmer temperatures of 70 to 75 degrees Fahrenheit, and up to 20 days in cooler temperatures.
Potting and Repotting Black-Eyed Susan Vines
Black-eyed Susan vines grown in large pots with vertical structures can make beautiful decorations outdoors as well as inside your home. You can set a pair flanking a front door or define the edges of a patio or outdoor sitting area. Indoors, a pot of climbing vine can brighten the corner of a sunroom or even a large, bright bathroom.
Indoor vines can even flower in the winter, provided they get plenty of sun and the temperature doesn't drop below 60 degrees Fahrenheit. Feed container plants (indoors or outdoors) every two to three weeks during the blooming period.
Move potted vines indoors so the vines can even flower in the winter, provided they get plenty of sun and the temperature doesn't drop below 60 degrees Fahrenheit. Feed indoor wintering container plants every two to three weeks during the cold season's blooming period.
Common Pests & Diseases
This showy vine is free of most serious insect or disease problems when grown outdoors, but indoors the plants can have problems with scale, spider mites, and whiteflies. Typically, these can be managed with neem oil or horticultural soap.