Ornamental · Acanthaceae
Black-eyed Susan Vine
Thunbergia alata
Set it in full sun, steady water, and something to climb, and this twining annual carries color from summer to frost.
Full sun
Every 2–4 days
50–86°F · 10–30°C
70–100 days
Overview
Few climbers set a mood as easily as the black-eyed Susan vine, a fast twiner kept for the long, cheerful run of bloom it throws across a season. Though it began as a tender perennial from East Africa, most gardens treat it as a warm season annual, letting it dress a trellis, a fence, or a hanging basket over a single summer. Flowers in orange, yellow, and white, most carrying a dark eye, lend it both color and its name.
Its appeal lies in how quickly it covers a space and how long it stays in flower. Hand it something to wind around and it will drape an arbor or pour over the lip of a container, climbing to 3 to 8 feet (91 to 244 cm) in one season. Bloom carries from early summer through to frost, and the show tends to look loveliest in late summer and fall, after the harshest heat has moved on.
Few plants ask for so little while giving so much, which makes this an easy plant to fold into a routine: it wants only sun, water, and a support to reach for. Keep the soil from baking dry through a heat wave and pinch back the young stems for a fuller shape, and it returns months of color in kind.
Care
The short version: full sun to part shade, with afternoon shade where summers run hot. Keep the soil evenly moist so it never dries out, give it rich, well-drained ground and a support to climb, and feed it through the growing season.
Light
The black-eyed Susan vine flowers most freely in full sun, yet it handles part shade without complaint. Where summers turn punishing, a measure of afternoon shade takes the edge off the heat, while too little light leaves you with a leggy plant heavy on foliage and short on bloom.
Water
Hold the soil evenly moist and water often enough that it never dries through, roughly every 2 to 4 days in warm weather. A vine left to go dry in a hot, dry spell sheds its buds and flowers, so keep it from running short across the summer.
Soil
Set it into rich, fertile, well-drained ground carrying steady moisture and a good helping of organic matter. The ground should keep its moisture without turning soggy, which serves garden beds and containers alike.
Temperature
It settles in happily between 50°F and 86°F (10°C to 30°C) and holds no tolerance for frost. The bloom eases off through the peak of summer heat, then surges back as the air cools toward late summer and fall.
Humidity
Everyday outdoor humidity suits it well, so there's no figure to chase. Good airflow matters more in this case, since still, crowded growth opens the door to spider mites and whiteflies, above all on plants kept inside.
Feeding
Offer it food once a month across the spring and summer growing season using a balanced, general-purpose fertilizer. Regular feeding keeps a quick grower like this clothed in leaf and flower, with no single nutrient falling short.
Pruning
Pinch the young stems early on to draw out side branching and a fuller, bushier vine. As the season runs, cut back whatever turns leggy or overgrown to hold the shape neat and draw out further flowers.
Repotting
For container plants, refresh or pot up each spring to open room for the roots and renew the mix. Stay alert to roots circling the pot or pushing through the drainage holes, water that runs straight through, and stalled growth, each a sign it has outgrown its place.
Size & spacing
Trained on a support, the vine reaches 3 to 8 feet (91 to 244 cm) in height and spreads 3 to 6 feet (91 to 183 cm) across in a single season. Allow it space and a trellis or fence to twine through so it has somewhere to travel.
When to plant
Warmth is what this vine lives for, and frost is its undoing. Sow the seeds indoors in early spring, move the plants outside only after the chill has truly gone and the ground has warmed, and let the flowers carry you from early summer until frost draws the season to a close.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 6-8 weeks before last spring frost
- Plant: after last spring frost when soil and air have warmed
- Harvest: early summer to frost; best bloom in late summer and fall after peak heat moderates
Hardiness
USDA hardiness zones: 10–11
Temperature: down to -1°C
Troubleshooting
Nearly every hiccup with this vine comes down to heat, light, or pests, and the flowers or the leaves are usually the first to tell on it. Catch those early cues and you can step in before the bloom thins out. Pair what you notice with the entries below, then act while there's still time to turn it around.
Buds and blooms falling away through a hot, dry stretch
What looks alarming is simply heat and drought stress, not a disease, and it surfaces whenever the soil bakes dry during a long hot run. To protect itself, the vine pauses its flowering, and it resumes once cooler weather arrives in late summer and fall. Hold the moisture even with regular water, lay mulch over the roots to keep them cool, and offer afternoon shade in places where summers turn fierce.
Fix:
- Water regularly to keep soil evenly moist during heat
- Provide afternoon shade in hot climates
- Mulch to conserve soil moisture and keep roots cool
Speckled, tacky leaves marked by webbing or tiny pests
Stressed plants and those kept indoors tend to draw in spider mites, whiteflies, aphids, or scale, which leave the leaves dotted, sticky, or laced with fine webbing. Flip a leaf to spot what's there, then drive them off with a firm jet of water before treating the undersides with insecticidal soap or horticultural oil. A second round of treatment and better air movement, indoors especially, keeps them from returning.
Fix:
- Rinse foliage with a strong spray of water to dislodge mites and aphids
- Apply insecticidal soap or horticultural oil, covering leaf undersides
- Repeat treatments and improve airflow for indoor plants
Lush foliage, hardly a flower in sight
When a vine stretches long and leafy yet declines to bloom, too much shade is usually behind it. Full sun is where this plant flowers freely, so shift a container to a brighter corner and try for at least several hours of direct light each day. Once it gets the sun it craves, the blooms arrive on their own.
Fix:
- Move container plants to a sunnier spot
- Site in full sun to part shade with at least several hours of direct sun
Toxicity
A welcome note for homes with animals: the black-eyed Susan vine carries no listing as toxic to pets or people. It belongs easily in a garden shared by cats, dogs, and inquisitive children. A large mouthful of foliage might bring on a brief touch of stomach upset, as with any plant, so steering pets away from chewing it remains a sensible habit.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
A nosy cat can nibble the leaves with no ill effect, as this vine doesn't appear on the ASPCA toxic list. Should it work through a big mouthful of greenery, expect maybe a touch of drooling or a hairball, and little else.
Dogs Safe
This is a safe plant to keep around dogs. At worst a quick nibble brings on a short spell of mild stomach upset, much like most ornamental foliage would.
Horses Safe
Horses have no recorded toxicity to worry about here. A bit of grazing on a wandering vine causes no genuine harm.
Rabbits Safe
The foliage is safe for rabbits to browse. As you would with any fresh green, offer it slowly so an abrupt diet shift doesn't upset their gut.
Livestock Safe
There is no documented danger to cattle, goats, or sheep from this vine, so a mouthful out in the pasture gives no cause for concern.
Birds Safe
No known threat to birds comes from this plant. Backyard hens are free to peck at its leaves and seeds with no trouble at all.
People Safe
No poisoning in people has ever been recorded, and the vine is grown for its flowers, not for the table. Still, keep watch over small children, who ought not to be tasting garden plants in any case.
As with any plant, ingestion of plant material may cause mild, transient stomach upset in pets.
Varieties
Black-eyed Susan vines reach the market mostly as seed series chosen for a spread of warm flower colors. The selections below are the ones you'll come across most.
Susie series
A well-loved seed series offering orange, yellow, and white, available either with the signature dark eye or without it.
Arizona series
A strong-growing series in warm tones of orange, apricot, and gold, every flower framed by a dark center.
Spanish Eyes
Wraps soft terracotta and apricot tones around a dark eye, lending a warmer and more muted character.
Blushing Susie
Brings together tender shades of apricot, rose, and ivory, frequently with eyes that soften away rather than stand out.
Alba
A crisp white-flowered selection that holds onto the trademark dark purple-black eye.
How to propagate
Multiplying this vine takes little fuss, whether you open a fresh seed packet each spring or root cuttings to see a cherished plant safely through winter.
SeedEasy
Start indoors 6-8 weeks before last frost, or sow directly outdoors after the last frost. · Germinates in about 1-3 weeks; weeks to a few months to a flowering vine
Growing this annual vine from seed is the standard route, and a forgiving one at that. Begin it indoors 6 to 8 weeks before your last frost, or drop the seeds into warm ground once frost is behind you, and germination follows in about one to three weeks. After that, give it a few weeks to a couple of months to climb its support and break into flower.
Stem cuttingsModerate
Take cuttings in late summer for overwintering indoors. · A few weeks to root
Taking cuttings is the way to usher a treasured plant through the cold months. Snip them in late summer, let them root across a few weeks, and settle the young plants on a warm, sunny sill until spring returns. The effort runs higher than sowing seed, yet it keeps a variety you'd like to grow once more.
Myths
Black-eyed Susan vine is the same plant as the Black-eyed Susan wildflower.
The shared name and the dark center are all these two have in common. Black-eyed Susan vine (Thunbergia alata) is a tender twining annual climber in the family Acanthaceae, native to East Africa. By contrast, the wildflower Black-eyed Susan (Rudbeckia hirta or fulgida) stands upright as a daisy-like perennial or biennial in the aster family. They are completely different plants with only the look of the bloom's eye to connect them.