Family: Acanthaceae
Common name: Bengal clockvine, Bengal trumpet, Blue skyflower, Blue thunbergia, Blue trumpet vine, Clockvine, Skyflower, Skyvine, Bengal clock-vine, Blue sky flower, Blue sky vine, Blue skyflower, Giant thunbergia, Green trumpet vine, Indian sky flower, Large flowered thunbergia, Skyflower vine, Thunbergia, Trumpet vine
Bengal Clockvine is a fast-growing, tropical, flowering vine with beautiful blue or white flowers and lush green leaves. The root system of the plant is quite substantial, with a very deep tap root that is difficult to remove.
Native to Asian countries like China, India, Bangladesh, and Nepal, these plants are now considered invasive weeds in certain parts of the world because of their capability to smother surrounding vegetation or even large trees.
Plant Characteristics
These vines can reach a height of 10-15 meters with their rope-like, strong stems, climbing on trellises, pergolas, supporting structures, balcony railings, or even small trees. Bengal clockvine leaves vary in shape, but they generally have a heart-shaped base and an elongated tip.
They can be serrated or smooth, lobed or entire, heart-shaped or oblong, sometimes having differently-shaped leaves on a single stem. Leaves are dark, glossy green, 10-15 cm in length with prominent venation.
Flowers are larger compared to other species of Thunbergia like Thunbergia erecta or Bush clockvine, Thunbergia fragrans or Sweet clockvine. They are trumpet-shaped with 5 fused petals and a yellow-colored throat.
Bengal clockvine flowers grow in clusters of 3-10 with pale blue or white flowers dotting the foliage, making the plant a stunning showstopper for your garden. Flowers are usually seen in spring and summer, though they can flower almost throughout the year in warm, tropical countries.
These Bengal clockvine flowers attract butterflies, birds, and bees to the garden to help pollinate them. After pollination, the plant produces small rounded fruits that are about 1 cm in diameter, though these are not commonly seen in garden plants.
Gardening Tips
The plants need good sunlight to encourage flowering, though they are capable of tolerating partial shade.
Water the plants especially in dry, summer months and fertilize once a month during the flowering season. The plants might go into slow-growth mode in winter, when you can cut down on watering and fertilization.
It’s crucial to provide the plant with a supporting structure to climb on, without which they will trail on the ground affecting growth and flowering. Bengal clockvines might also climb on surrounding plants, cutting off sunlight and smothering them.
Uses of Bengal Clockvine
Bengal clockvines are mostly grown as ornamental plants in home gardens, parks, and landscaped areas. They make excellent screen plants to keep areas in the garden private.
If allowed to climb on a separator screen or fence, they can cover the fence quickly giving privacy to the garden. The beautiful blue or white flowers can keep the garden beautiful.
Bengal clockvines have a very long blooming period during which they attract butterflies, bees, insects, and small birds into the garden, thus helping in pollination of other plants as well.
Propagation
Propagation is very easily done through stem cuttings. Seed propagation and layering is also possible.
Photographed at: Raman Research Institute, Bangalore and Manjapra, Kerala
