Thunbergia grandiflora (Blue Sky Flower)

Scientific Name

Thunbergia grandiflora (Roxb. ex Rottl.) Roxb

Common Names

Blue Sky Flower, Bengal Clockvine, Bengal Trumpet, Blue Thunbergia, Blue Trumpetvine, Clockvine, Skyflower, Skyvine


Flemingia grandiflora, Pleuremidis grandiflora, Thunbergia adenophora, Thunbergia chinensis, Thunbergia cordifolia, Thunbergia lacei

Scientific Classification

Family: Acanthaceae
Subfamily: Thunbergioideae
Section: Thunbergia


Color: Pale blue
Bloom Time: Midsummer to late fall


Thunbergia grandiflora is a vigorous evergreen vine with thick tuberous roots from which emerge rope-like stems holding up to 5 inches (12.5 cm) long, dark green leaves with a slightly toothed margin. From mid-summer to late fall appear the beautiful, pale blue, cup-like flowers with pale yellow to cream blue striped centers.

Thunbergia grandiflora (Blue Sky Flower)
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USDA hardiness zone 8a to 11b: from 10 °F (−12.2 °C) to 50 °F (+10 °C).

How to Grow and Care

Plant Thunbergia seedlings outdoors after all frost danger passes, or start your own seeds indoors six weeks before the last expected frost. With proper care, the vines remain in bloom from midsummer until fall frost.

Spread 2 inches (5 cm) of compost over a well-drained garden bed that receives full morning sunlight and light afternoon shade. Site the bed near a trellis, fence, or similar 5 to 8 foot (1.5 to 3.4 m) tall support. Work the compost into the top 8 inches (20 cm) of soil.

Plant the seedlings along the base of the support. Space the plants 12 inches (30 cm) apart. Plant the seedlings at the same depth they were growing at previously.

Water Thunbergia deeply once a week, providing approximately 1 inch (2.5 cm) of water during irrigation or enough to keep the top 6 inches (15 cm) of soil evenly moist. The plants require less irrigation during rainy weather, and they may require twice weekly irrigation during times of dry, hot weather. See more at How to Grow and Care for Thunbergia.


Native to China, India, Nepal, Indochina, and Burma and widely naturalized elsewhere.



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