Named for its resemblance to the popular hardy garden flower black-eyed Susan (Rudbeckia spp.), black-eyed Susan vine (Thunbergia alata) is instead a tender perennial climbing 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 they bloom for many weeks in 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, 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. It can be particularly aggressive where it grows year-round and is considered invasive in many areas, including Hawaii and Mexico. A number of different cultivars are available with many different flower colors, including white, pink, rose, and purple.
|Botanical Name||Thunbergia alata|
|Common Name||Black-eyed Susan vine,|
|Plant Type||Flowering vine, annual or perennial|
|Mature Size||3 to 8 feet tall and 3 to 6 feet 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|
|Native Area||East Africa|
How to Grow Black-Eyed Susan Vine
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.
It's best to provide vertical structure 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.
This showy vine is free of most serious insect or disease problems when grown outdoors, but indoor plants can have problems with scale, spider mites, and whiteflies. Typically, these can be managed with neem oil or horticultural soap.
Grow these plants in full sun to part shade; some afternoon shade is beneficial, especially in warmer climates.
Plant 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
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 summer of over.
Feed the plants 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.
Varieties of Black-Eyed Susan Vines
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
Growing Black-Eyed Susan Vine in Containers
Black-eyed Susans 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.
Landscape Uses of Black-Eyed Susan Vine
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.