Thunbergia grandiflora
Common Name: blue trumpet vine 
Type: Vine
Family: Acanthaceae
Native Range: Northern India
Zone: 10 to 11
Height: 15.00 to 30.00 feet
Spread: 3.00 to 6.00 feet
Bloom Time: August to September
Bloom Description: Lavender blue
Sun: Full sun to part shade
Water: Medium
Maintenance: Low
Suggested Use: Annual
Flower: Showy
Leaf: Evergreen

Culture

Winter hardy to USDA Zones 10-11 where it is best grown in organically rich, fertile, medium moisture, well-drained soils in full sun to part shade. Appreciates some light afternoon shade in hot summer climates. In St. Louis, it is best grown as an annual vine. New plants may be purchased in spring each year. In the alternative, plants may be grown from seed started indoors 6-8 weeks before last spring frost date. Container plants may be overwintered indoors in a warm sun room and/or cuttings may be taken in late summer for overwintering.

Noteworthy Characteristics

Thunbergia grandiflora, commonly called blue trumpet vine, clock vine, sky vine or sky flower, is a woody-stemmed, evergreen, tropical, twining climber. It grows to 15-30’ long in frost free areas. When grown as an annual, it grows to 6-8’ long in a single season. It is native to India. Elliptic to heart-shaped dark green leaves (to 4-8” long) are covered with soft hairs. Trumpet shaped flowers (to 3”) are lavender blue with yellow throats. Flowers appear singly or in clusters (racemes) in summer to early fall. Flowers bloom year round in tropical climates.

Genus name honors Carl Peter Thunberg (1743-1828), Swedish botanist. He travelled in South Africa and Japan and became professor of botany at Uppsala.

Specific epithet means large-flowered.

Problems

No serious insect or disease problems. Watch for scale, spider mites and whiteflies.

Garden Uses

Trellises, arbors, fences or other structures in areas where winter hardy. Hanging baskets and other containers when grown as an annual. Houseplant.