Thunbergia alata

Thunbergia alata - 'Black-eyed Susan'
Thunbergia alata – ‘Black-eyed Susan’

Thunbergia alata or ‘Black-eyed Susan’ is the best known of the genus, some species are regarded as invasive.

Thunbergia are generally regarded as frost tender and in cooler climates are best planted in a sheltered sunny spot in a moist, humus rich, well drained soil.

Thunbergia alata is widely grown in hanging baskets, being such as easy care and hardy plant especially in Zones 9 – 11 where they can be grown outdoors. However the popularity does not stop in the warmer zones.

They are also loved in cooler climates where Thunbergia alata or ‘Black-eyed Susan’ can be grown on an enclosed patio with little difficulty.

Flower color varies from orange with a deep red to black eye, and also white, red and cream. You can buy mixed packets of seeds and create a good colorful display. They are widely grown from Florida to New York and Virginia to California.

Growing from seed

Plants grow quickly from seed and will begin flowering once they reach around 3ft tall. In cooler zones seeds are best started early indoors, late winter to early spring to give them a head start.

In warmer areas seeds can be planted directly into the ground in spring, as soon as the weather warms a little.

In cooler climates Thunbergia alata can also be grown as an annual, it is fast growing and with the masses of flowers adds color to the garden fairly quickly.

Thunbergia Varieties

Many species are regarded as invasive, check with local nurseries for specific information.

  • Thunbergia alata or ‘Black-eyed Susan’
    Well known climbing plant.
  • Thunbergia mysorensis or ‘Clock Vine’ is a n evergreen climbing vine native to India. Showy yellow and red/brown flowers.
  • Thunbergia grandiflora Native to India and ism a vigorous fast growing vine, can be invasive.
  • Thunbergia erecta or ‘Bush clock-vine’or ‘Kings Mantle’ is a sprawling shrub native to tropical Africa. Responds well to pruning to keep it in shape.
  • Thunbergia fragrans or ‘Sweet clock-vine’ vigorous fast growing vine, can be invasive.
  • Thunbergia laurifolia or ‘blue trumpet vine’ is native to India and Africa, regarded as invasive.
  • Thunbergia annua ‘Laurel Clockvine’ vigorous fast growing vine, can be invasive.