Ornamental · Acanthaceae
Black-eyed Susan Vine
Thunbergia alata
Hand it full sun, steady water, and something to climb, and this twining annual pumps out flowers from summer to frost.
Full sun
Every 2–4 days
50–86°F · 10–30°C
70–100 days
Overview
Quick to twine and quick to flower, the black-eyed Susan vine climbs for the sake of its long parade of cheerful blooms. Origin is a tender perennial out of East Africa, yet most gardeners run it as a warm season annual, sending it up a trellis, fence, or hanging basket across a single summer. Those bright orange, yellow, and white flowers, the majority stamped with a dark eye, are exactly what hand the plant its name.
Climbing fast and flowering for months, this vine pays you back in full. Hand it something to wind around and it will blanket an arbor or tumble from a pot, stretching 3 to 8 feet (91 to 244 cm) over a season. Flowering carries from early summer straight through to frost, and the show usually peaks in late summer and fall once the harshest heat lets up.
Sun, water, and a climbing frame are about all this easy plant asks for. Keep the soil from baking dry in a heat wave, pinch the young stems to build a fuller vine, and you collect months of nonstop color.
Care
The short version: full sun to part shade, plus afternoon shade where summers turn hot. Hold the soil evenly moist so it never bakes dry, plant it in rich, well-drained ground next to a support it can climb, and feed steadily across the growing season.
Light
The fullest flower display comes under full sun, yet black-eyed Susan vine handles part shade without a fuss. Across brutal summers, a stretch of afternoon shade takes the edge off the heat, while skimping on light leaves you a leggy plant heavy on foliage and short on blooms.
Water
Hold the soil evenly moist and water often enough that it never dries out, which lands at roughly every 2 to 4 days through warm weather. Let a vine run dry during a hot, dry spell and it sheds its buds and flowers, so keep it well supplied all summer long.
Soil
Set it into rich, fertile, well-drained ground carrying steady moisture and a good helping of organic matter dug in. You want soil that grips water yet never turns soggy, a balance that serves garden beds and containers alike.
Temperature
It thrives in the band between 50°F and 86°F (10°C to 30°C) and carries no tolerance for frost. Flowering eases off at the height of summer heat, then rallies hard as cooler air settles in over late summer and fall.
Humidity
Plain outdoor humidity suits it fine, so skip chasing a number. What carries far more weight is good airflow, because stale, crowded growth rolls out the welcome mat for spider mites and whiteflies, particularly on plants kept indoors.
Feeding
Feed once a month across the spring and summer growing season using a balanced, general-purpose fertilizer. Regular feeding keeps a quick grower like this pushing leaf and flower without letting any single nutrient fall short.
Pruning
Get in early and pinch the young stems to drive side branching and a fuller, bushier vine. As the season runs, snip back any leggy or runaway stems to hold its shape and draw out still more flowers.
Repotting
For container plants, refresh or pot up each spring to open room for the roots and renew the mix. Keep an eye out for roots circling the pot or poking through the drainage holes, water that runs straight through, and stalled growth, each one a flag that it has outgrown its home.
Size & spacing
Trained up a support, the vine climbs 3 to 8 feet (91 to 244 cm) tall and fans out 3 to 6 feet (91 to 183 cm) wide within a season. Spare it the room and offer a trellis or fence to twine through so it always has somewhere to head.
When to plant
Warmth is what this vine runs on, and frost stops it cold. Get the seeds going indoors in early spring, move the plants outside only after the chill has fully lifted and the soil has warmed, and then enjoy flowers rolling from early summer until frost closes the season.
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
Almost every snag with this vine comes back to heat, light, or pests, and the flowers or leaves flag it first. Catch those opening signals and you can act before the blooms fall away. Pair what you spot with the entries below, then move while it still does some good.
Buds and blooms letting go when the air turns hot and dry
What you are seeing is heat and drought stress rather than any disease, and it kicks in once the soil bakes dry through a hot run. To guard itself, the vine pauses its flowering, then surges back as the weather softens into late summer and fall. Stay ahead of it: water on a steady schedule for even moisture, lay mulch over the roots to hold them cool, and shade the plant in the afternoon wherever 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 carrying webbing or tiny insects
Stressed plants and indoor vines draw in spider mites, whiteflies, aphids, or scale, and the giveaway is foliage gone speckled, sticky, or laced with webbing. Flip a leaf to spot who is feeding, then blast them off with a forceful jet of water and follow through with insecticidal soap or horticultural oil worked across the undersides. Run the treatment again, and loosen up the airflow, which counts double for anything growing inside.
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
Loads of foliage, hardly a bloom in sight
When a vine stretches long and leafy yet skips the flowers, too much shade is almost always behind it. Full sun is what brings on the best display, so shift a container to a brighter corner and chase at least several hours of direct light each day. Hand it the sun it craves and the blooms come right along.
Fix:
- Move container plants to a sunnier spot
- Site in full sun to part shade with at least several hours of direct sun
Toxicity
Households with animals get a happy answer here: the black-eyed Susan vine carries no toxic listing for pets or people. Grow it freely where cats, dogs, and inquisitive children all roam the garden. As with any plant, a large mouthful of foliage could spark a brief bout of stomach upset, so steering pets away from chewing it remains a smart move.
Safe for
People · Cats · Dogs · Horses · Rabbits · Livestock · Birds
Cats Safe
A nosy cat is welcome to chew the leaves, because this vine never made the ASPCA toxic list. Pack away a big mouthful of any greenery and you might see a touch of drooling or a hairball, and that is the whole story.
Dogs Safe
Dogs do just fine alongside this plant. A nibble, at worst, brings on a brief spell of mild stomach upset, exactly what most ornamental foliage does.
Horses Safe
Horses have no recorded toxicity to worry about here. A bite of a stray vine while grazing will cause no real harm.
Rabbits Safe
Rabbits browse the foliage with no trouble at all. Bring it in slowly, as with any fresh green, so a sudden diet swing does not loosen their gut.
Livestock Safe
Cattle, goats, and sheep meet no documented danger from this vine, so a mouthful out in the pasture gives you nothing to fret over.
Birds Safe
Birds run into no known threat from the plant. Backyard hens are free to peck the leaves and seeds with no trouble.
People Safe
People have no record of poisoning from it, and the vine earns its place for flowers, not for the table. Just keep watch over small children, who really should not be tasting garden plants anyway.
As with any plant, ingestion of plant material may cause mild, transient stomach upset in pets.
Varieties
Black-eyed Susan vines mostly reach you as seed series bred for a spread of warm flower colors. Here are the ones you are most likely to come across.
Susie series
A favorite among seed series, offering orange, yellow, and white blooms that come with or without the trademark dark eye.
Arizona series
A strong-growing series running through warm orange, apricot, and gold, every flower framed by a dark center.
Spanish Eyes
Wraps soft terracotta and apricot tones around a dark eye to land a warmer, more muted look.
Blushing Susie
Folds together gentle apricot, rose, and ivory, frequently with eyes that melt away instead of standing out.
Alba
A crisp white-flowered form that holds onto that signature dark purple-black eye.
How to propagate
Multiplying this vine takes little effort, whether you kick off fresh from a seed packet each spring or strike cuttings to carry a favorite plant clear 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
Seed is the standard route for this annual vine, and it could hardly be simpler. Sow indoors 6 to 8 weeks before your last frost, or drop seed right into warm ground once the frost has cleared, and sprouts break through in about one to three weeks. After that, count on a few weeks to a couple of months for the vine to scramble up and burst into flower.
Stem cuttingsModerate
Take cuttings in late summer for overwintering indoors. · A few weeks to root
Cuttings let you usher a treasured plant straight through winter. Snip them in late summer, give them a few weeks to root, and park the young plants at a warm, sunny window until spring arrives. It demands a touch more attention than seed, yet it preserves a variety you are keen to grow again.
Myths
Black-eyed Susan vine is the same plant as the Black-eyed Susan wildflower.
The shared name and a 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 that simply resemble each other at the bloom's eye.