Black-eyed Susan vine plant is a tender perennial that is grown as an annual in temperate and cooler zones. You can also grow the vine as a houseplant but be wary as it may grow to 8 feet (2+ m.) in length. Black-eyed Susan vine care is most successful when you can mimic the plant’s native African climate. Try growing a black-eyed Susan vine indoors or out for a bright cheery flowering vine.
I. Appearance and Characteristics
Thunbergia alata, commonly called black-eyed Susan vine, is a herbaceous perennial climbing plant species in the family Acanthaceae. It is native to Eastern Africa, and has been naturalized in other parts of the world.
It is grown as an ornamental plant in gardens and in hanging baskets. The name ‘Black-eyed Susan’ is thought to have come from a character that figures in many traditional ballads and songs. In the Ballad of Black-eyed Susan by John Gay, Susan goes aboard a ship in-dock to ask the sailors where her lover Sweet William has gone. Black-eyed Susan is also a name given to other species of flowers in the genus Rudbeckia.
hunbergia alata has a vine habit, and can grow to a height of 5 metres (16 ft) high in warmer zones, or much less as a container plant or as an annual. It has twining stems with heart or arrow-shaped leaves. The three and a half to seven and a half centimeters long and two and a half centimeters wide leaves are triangular to heart-shaped. Their edges are wavy and both surfaces are hairy. The leaf blades sit on up to six and a half centimeters long petioles, which attach at a distance of four and a half to 13 centimeters on the one to one and a quarter millimeter thick stem axis.
The hairy, mostly orange-yellow flowers have five petals and appear throughout the growing season, which grow on up to eight and a half centimeters long inflorescence axes. They typically are warm orange with a characteristic dark spot in the center. The central two centimeter long corolla tube is black-violet. Each of the single flowers has two triangular to oval, hairy bracts that taper towards the outside. They are 18 to 20 millimeters long and nine to ten millimeters wide. The serrated calyx is about two millimeters long and has between 15 and 17 awl-shaped lobes. The corolla tube measures around four centimeters and shows five two centimeter large corolla lobes with right-hand covering buds on the outside.
The plant flowers from mid-summer to the first frost, but it will flower all year round in milder, frostless climate zones.
The 16 to 18 millimeter long fruits are finely hairy. At the base they have a diameter of seven millimeters. The four seeds measure 3.5 millimeters.
It is used all around the world as a garden plant, but has managed to “escape” to the wilderness, naturalizing in tropical and temperate forests. It has been widely reported as Invasive species, especially in the Caribbean and Pacific islands, from Mexico to Colombia, and in Japan, due to the fast growing of the plant; the ease of wild pollination during sporadic flowering times; its vine-growing strategies that strangle or create shadow on other plants; its difficulty to eradicate by hand (as it leaves underground rhizomes that rapidly grow back); its lack of usual predators in non native regions; plus, people who are unaware of its harmful nature to other plants in the wilderness tend to admire its beauty and might opt not to remove it.
II. How to Grow and Care
Sunlight
If you grow your Black-eyed Susan vines in full sun, you’ll receive the most flowers and the healthiest plants. And your plants should get at least six hours of direct sunlight on most days. Although the Black-eyed Susan vine can tolerate some shade, flowering may be affected.
The plant will continue to bloom as long as it is exposed to enough sunlight and the temperature does not drop below 60 degrees Fahrenheit.
It is best to grow the plants in the afternoon shade in dry or hot locations because they do not perform well when exposed to direct sunlight.
Temperature & Humidity
In the summer, the average room temperature is 70 degrees Fahrenheit (21.1 degrees Celsius). In the winter, the ideal temperature is 47.2 – 53.6- degrees Fahrenheit (8. 3 – 12.2 degrees Celsius). They are commonly grown as annuals in cooler climates.
Because black-eyed Susan vines are actually perennials, which means they come back year after year if you live outside of their hardiness zones, you can put them in a container and bring them inside for the winter.
Although humidity usually is not an issue for these plants, they might suffer in arid conditions, so keep the soil moist. You can increase the humidity by misting the plant, grouping plants together, and having a humidifier close to the plant.
Watering
Thunbergia indoors doesn’t like wet soil, but they also don’t like it when it’s dry. Once a week is ideal in maintaining their moisture. Throughout the growing season, the plants demand regular and deep watering.
Medium moisture, but not wetness, should be maintained in the soil. Shredded leaves or organic mulch are also ideal for these annual plants. This type of mulch gives the bed a natural appearance while also enriching the soil.
Soil
Black-eyed Susan vines like a well-draining soil that is rich in organic matter with a fairly neutral soil pH (6.6 to 7.7). It can be helpful to work several inches of compost into the soil before planting.
Fertilizing
Every plant requires fertilizer since it contains additional nutrients that plants need. By doing this, the Black-eyed Susan vines grow swiftly and frequently flower all summer long. You can fertilize your plant using liquid fertilizer every two weeks.
Fertilizer with a higher potassium content is beneficial from the start of budding. Keep in mind that excessive fertilization might result in excessive growth and fewer blooms.
Propagation
There are many ways to propagate black-eyed Susan vine, but the most common is by taking stem cuttings to root. Done in fall, this is a good way to perpetuate plants over the winter in colder regions. Here’s how to do it:
- In fall while the plant is still actively growing, use clean sharp pruners to snip 4- to 6-inch segments of healthy stem, making the cut just below a stem node.
- Plant the cutting in a small container filled with ordinary potting mix. No covering is required.
- Set the pot in a bright, warm location, such as a sunny window, to grow over the winter.
- In the spring after outdoor temperatures are reliably above 60 degrees Fahrenheit, the root cutting, now showing active growth, can be transplanted into the garden or into outdoor containers.
How to Grow from Seed
Black-eyed Susan vine is easy to grow from seed. Seeds can be relatively expensive, but that’s because this plant’s seed is difficult to collect. You can start seed indoors about six to eight weeks before your projected last frost date or direct-seed in the garden after the danger of frost has passed. Soak the large, hard seeds in water for a day or two before planting.
Black-eyed Susan vines don’t like having their roots disturbed, so it helps if you start the seed in peat or paper pots that will biodegrade when planted with the seedling. Plant the seeds about 1/4 inch deep, and expect them to germinate within two to three weeks.
Potting and Repotting
This plant makes an excellent plant for hanging baskets, window boxes, or large mixed containers where it serves as a “spiller” plant. Ordinary commercial potting mix in any well-draining container will suffice. In hanging baskets, it’s typical to plant two or three plants in a 10- to 12-inch plastic pot that includes a catch-tray, suspended with wires that will allow the vines to climb.
Most gardeners grow black-eyed Susan vine as an annual, pulling it from containers at the end of the growing season, but it’s also possible to move potted plants indoors to continue growing through the winter as a houseplant. But indoor specimens will need plenty of sun, which can be hard to come by during the shortened winter days. Supplemental light may be required in order to keep the plants blooming.
Overwintering
When grown as an annual, these plants are simply pulled from the ground and discarded in the late fall, which helps avoid self-seeding. In warm-winter regions where black-eyed Susan vine can be grown as a perennial, it’s best to keep watering and feeding actively through the winter.
Pests and Diseases
Common Pests & Plant Diseases
Black-eyed Susan vine isn’t prone to many problems, particularly if the plant has plenty of sun, water, and air circulation. However, whiteflies and spider mites can be potential problems, especially during hot weather or if the plant is brought indoors where there is dry heat.1 Look out for small insects on the plant, as well as leaf and stem damage. Treat any outbreaks quickly with insecticidal soap.
Common Problems
There are very few common complaints with black-eyed Susan vine, though gardeners in warm-weather regions sometimes complain about the plant’s habit of self-seeding to the point of invasiveness. Even in cold-weather regions, you may dislike the way volunteers readily spring up around areas where plants were growing the previous year. But these volunteers are easily plucked out, and in cold winter zones, they do not persist to colonize.
III. Thunbergia Varieties and Similar Plants
These Thunbergia plants also have similar plants and varieties. And I know if you know these beauties, you also want them in your collection!
Here are some of them:
- Black-eyed Susan Indian Summer
Because these plants do not live for a long time, they are sometimes known as short-lived perennials. These plants can reach a height of 5 to 8 inches, and they can even reach a height of more than 8 inches. From the top to the right, the plant grows. They have a vivid yellow color with a brown core, making your landscape look even more gorgeous.
- Black-eyed Susan Goldsturm
This plant resembles a black-eyed Susan, which has yellow flowers and a black spot in the middle. When these plants blossom, they naturally attract neighboring butterflies. If you cultivate this in your garden, it will spread slowly up to a maximum of 14-18 inches. Its height ranges from 5 to 11 inches and can occasionally exceed 12 inches.
- Black-eyed Susan Toto
The plant is noted for its beauty and ease of care. Its flower is a bright golden yellow color that matures to the dark brown color in the middle. This plant can grow to a height of 4 to 12 inches and spread to a width of 16 to 18 inches. Because this plant grows and takes up a lot of areas, it’s best to plant it in the ground rather than in a container.
IV. Uses and Benefits
Black-eyed susan vine is a perennial that you will often see used in hanging baskets, which show off its long, trailing vines. In cottage, tropical, and ornamental gardens, it will ramble over the ground if left unstaked, or it can be trained to grow on walls, trellis, or other structures. Some gardeners will mix it with a contrasting vine, like morning glory or purple passionflower.
Find Where to Buy the Best Black-eyed Susan Vine (Thunbergia alata)
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