In much of the warmer world, Thunbergia alata is well known as a fast-growing, long-flowering, friendly vine. In its native South Africa it is a general favourite as it is not fussy about soil, needs only moderate water, doesn't go rampant, is mostly evergreen and covers ugly places beautifully.
Thunbergia alata will bloom all year long if night temperatures are above 16°C (60°F). This much loved plant has even been honoured in the standard set of South African postage stamps.
In our colder climates the Black-eyed Susan vine has recently become a firm garden favourite. Used as an annual they grow quickly and starts flowering at an early age. This twining vine blooms in a bright blend of creamy white, orange and yellow flowers all with the characteristic chocolate-purple centre which inspired the common name.
They are effective in window boxes, mixed containers or in patio containers, especially with a small trellis. Use in hanging baskets where the vine can twist around the basket supports.
The vines can grow to five or six feet high (150 to 180cm) if given good support and look stunning when left to climb over trellises, arbors, fences or other structures around the home. Alternatively, plant this creeper as a ground cover, or on a bank or terrace where it can be left to roam.
Sowing: Sow indoors in late autumn to late winter, or outdoors in spring
Sow seeds indoors 6 to 8 weeks before the last frost date for earlier blooms, or they may be grown in containers that can be overwintered indoors in a warm sun room.
They can be easily grown from seed sown directly in the garden after the last frost date. Choose a sunny position with moist soil, they cannot grow or bloom properly in the shade. Alternatively sow seeds directly into pots, containers or hanging baskets outdoors once temperatures have risen.
Sow onto moist seed sowing compost in trays or pots and just cover with 10mm (½in) of vermiculite.
Propagate at 20°C (68°F). Keep the compost moist at all times. Germination 14 to 21 days.
Plants initially grow quite slowly. Grow seedlings slightly on the dry side. The temperature can be lowered further as the seedlings become established - grow on at 15°C (60°F). Pot on the plug plants into larger pots if required.
Wait until the soil has warmed up and night temperatures remain above 10°C (50°F) to transplant outdoors.
Place transplants 15cm (6in) apart about 7cm (3in) from a support. Supports will be covered quickly after the plants become established.
Plants can be easily grown from seed sown directly in the garden after last frost date.
Soil should be moist and high in organic matter. Prepare the ground well and rake to a fine tilth. Sow seed sparingly covering with 6mm (¼in) of soil and water well. Thin the seedlings out so they are finally 30cm (12in) apart. Carefully replant thinned plants.
Hanging Baskets, Containers, Pot Plants, Conservatories, Clambering up Trellis, Obelisks and Trees. Also excellent when used as a groundcover.
Thunbergia is a genus of flowering plants in the Family Acanthaceae, native to tropical regions of Africa, Madagascar and southern Asia.
Thunbergia alata is one of some 90 old world species of which there are 12 in South Africa. Other species in cultivation are T. natalensis, T. grandiflora Roxb., the blue-flowered Bengal clock vine, from India, and T. gregorii S.Moore, the golden glory vine, with strong orange flowers but no dark 'eye', from tropical Africa and Ethiopia.
Clockvine on its own usually refers to Thunbergia grandiflora. Orange clockvine is the name of Thunbergia gregorii.
Thunbergia, named in 1780 by Retzius, honours Carl Peter Thunberg (1743-1828), a Swedish botanist, doctor, explorer and author who was perhaps the greatest pupil of Linnaeus.
He visited the Cape to study Dutch and the flora of the Cape (1772-1775) . He spent three years collecting at the Cape of Good Hope, collected 3100 specimens and published Flora Capensis.
Thunberg was so keen a collector that, when Japan was closed to all Europeans except the Dutch, he joined the East India Company as a surgeon so he could collect there. He visited to Japan, Jarva and Sri Lanka for 15 months. He wrote about his travels and Flora Japonica and presented his herbarium of 23,510 specimens and 25,000 insects to the University. Carl Peter Thunberg received many honours and was made a knight of the Royal Order.
Seed of Thunbergia alata, named by Bojer, a German botanist, was sent from Mauritius to England where it was first described by Sims in 1825. (Surprisingly the plant had cream-coloured, not orange flowers.)
The species name is from the Latin alatus meaning winged. It refers to the winged petioles but it could also allude to the seeds that have projections looking rather like wings.
Thunbergia alata is commonly known as Black-eyed Susan vine or just Black-eyed Susan. The name is also a name given to another species of flowers - Rudbeckia.
It 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.
- Additional Information
Packet Size 1 gram Average Seed Count 35 Seeds Family Acanthaceae Genus Thunbergia Species alata Common Name Black Eyed Susan Vine Other Language Names Swartoognooi (Afr.), isiPhondo (Zulu), Die schwarzäugige Susanne (Ger) Hardiness Half Hardy Annual Flowers Creamy white, orange or yellow flowers Natural Flower Time June till frosts Height 150 to 180cm (five or six feet high) Position Full sun or part shade. Time to Sow Sow indoors in late autumn to late winter, or outdoors in spring Germination 14 to 21 days at 18 to 21°C (65 to 70°F) Notes Very easy to grow. Vine/Climber