Black-eyed Susan vine Thunbergia alata
Black-eyed Susan vine (Thunbergia alata) is an annual flowering plant in the Acanthaceae family, native to Tropical East Africa. It grows 1.5–2.5 m (4.9–8.2 ft) tall and 50 cm–1 m (20 in–3.3 ft) wide, wants full sun and moderate water, and is hardy to about 2 °C (36 °F). Space plants about 40 cm (16 in) apart.
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Black-eyed Susan vine at a glance
| Type | Annual flowering plant |
|---|---|
| Family | Acanthaceae |
| Mature height | 1.5–2.5 m (4.9–8.2 ft) |
| Mature spread | 50 cm–1 m (20 in–3.3 ft) |
| Spacing | 40 cm (16 in) centre to centre |
| Sun | Full sun, at least 6 h of direct sun a day |
| Water | Moderate; drought tolerance low, waterlogging tolerance none |
| Soil pH | 5.5–7 |
| Cold hardiness | About 2 °C (36 °F) once established (roughly USDA zone 10) |
| Heat stress | Likely above about 36 °C (97 °F) |
| Flowering | about 9–14 weeks after planting, for 13–21 weeks |
| Days to maturity | About 90 days from planting |
| Wind tolerance | None |
| Pollinator value | Moderate |
| Edible | Not grown as food |
| Native to | Tropical East Africa |
| Common in gardens of | 🇿🇦 South Africa, 🇺🇸 United States, 🇹🇭 Thailand |
| Invasive in | Australia (environmental weed in Queensland and NSW), US (Hawaii): check local rules before planting |
Is Black-eyed Susan vine toxic?
- People: not well documented
- Cats: not well documented
- Dogs: not well documented
Toxicity is not well documented; not listed as a significant poison.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Black-eyed Susan vine
No well-documented helpful pairing. Group it with plants that like full sun and moderate water.
Questions about Black-eyed Susan vine
- How far apart should I plant Black-eyed Susan vine?
- About 40 cm (16 in) apart, centre to centre. A mature plant spreads 50 cm–1 m (20 in–3.3 ft).
- Does Black-eyed Susan vine need full sun?
- Full sun: at least 6 hours of direct sun a day.
- How much water does Black-eyed Susan vine need?
- Moderate water. Drought tolerance is low and waterlogging tolerance none.
- How cold-hardy is Black-eyed Susan vine?
- It tolerates about 2 °C (36 °F) once established, roughly USDA zone 10. As an annual it is usually planted out after the last frost.
- When does Black-eyed Susan vine flower?
- About 9–14 weeks after planting, for 13–21 weeks.
- Is Black-eyed Susan vine poisonous to cats and dogs?
- For cats it is not well documented; for dogs not well documented; for people not well documented. Toxicity is not well documented; not listed as a significant poison.
- What grows well with Black-eyed Susan vine?
- There is no well-documented companion pairing for Black-eyed Susan vine. Group it with plants that like the same sun (full sun) and water (moderate).
Sources and evidence
Evidence grade C (C: plausible, mixed evidence).
- RHS Plant Finder, Royal Horticultural Society
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
- CABI Invasive Species Compendium, CABI
Notes and assumptions
- Typical garden-form values; cultivars and local conditions differ.
- Tender perennial twiner grown as an annual outside frost-free climates (about zone 10 and warmer). Flowers continuously in warm weather.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
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- Bear’s breeches Acanthus mollis
- Bengal clock vine (blue trumpet vine) Thunbergia grandiflora
- Mexican petunia (Britton’s wild petunia) Ruellia simplex
- Nerve plant (fittonia) Fittonia albivenis
- Sunflower Helianthus annuus
- French marigold Tagetes patula