Thunbergia blue sky vine

Sky Vine

Thunbergia grandiflora

Fast growing sky vine reaches for the sky, decorated with ravishing summer flowers in blue with a hint of violet.

Blue flowering plants are a rarity in South Florida, and this vine’s incredibly beautiful clusters of blue-violet blooms light up the landscape with their unusual color and sheer size.

This is one fast-growing vine…like the famous bunny, it keeps going – and going – and going.

You’ll need plenty of room to fit one into your yard, but it can quickly fill in the blanks on an empty fence with just one or two plants.

These vines will climb over anything in their path, sending out wandering tendrils that can reach several feet out and grab onto a tree branch.

Deep green spade-shaped leaves form thick dense foliage, and the exquisite bloom clusters make fantastic cut flowers for your home, something we don’t take enough advantage of here in South Florida.

Plant specs and spacing

These vines blossom summer through fall. They need the warmth of Zone 10 and even there can defoliate in a cold winter.

This vine will grow in full sun but stays greener and prettier with a little shade protection from the blazing afternoon sunshine.

You must allow plenty of room for this rampant grower. Plant 8 feet from trees and shrubs.

To use along a fence, space vines 5 or 6 feet apart…or more.

Plant care

Amend the soil with top soil (or organic peat moss) and composted cow manure added to the planting hole.

Water on a regular basis.

Fertilize twice a year – in spring and fall – with a good granular fertilizer. Supplement feedings during warm weather with bone meal and/or liquid fertilizer to promote heavier flowering.

Cut back hard in early spring – mid to late March.

A.K.A. (also known as): Blue Sky Vine, Bengal Clock Vine (it’s a native to India and twines around in a clockwise direction)
LANDSCAPE USES: fence, pergola, large trellis or arbor, lattice enclosure for a patio or carport

Other vines you might like: Passion Vine, Petrea Vine

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Scientific name

Thunbergia grandiflora (Blue Thunbergia)

Thunbergia grandiflora (Roxb. ex Rottler) Roxb.


Flemingia grandiflora Roxb. ex Rottler; Pleuremidis grandiflora (Roxb.) Raf.; Thunbergia cordifolia(Nees)

Common names

Blue thunbergia, Bengal clock vine, Bengal clock-vine, Bengal clockvine, Bengal trumpet, Bengal trumpet vine, blue sky flower, blue sky vine, blue skyflower, blue trumpet vine, blue trumpetvine, clock vine, giant thunbergia, green trumpet vine, Indian sky flower, large flowered thunbergia, large-flowered thunbergia, sky flower, sky vine, skyflower vine, skyvine, thunbergia, trumpet vine.




This species is native to the Indian sub-continent, southern China and Myanmar.

Naturalised distribution (global)

Locations within which Thunbergia grandiflora is naturalised include tropical Australia, tropical South America, Central America, south-eastern USA and some oceanic islands with warm climates.

Introduced, naturalised or invasive in East Africa

Thunbergia grandiflora is naturalised in parts of Uganda (Dawson et al, 2008) and invasive in parts of Tanzania (Tropical Biology Association 2010).


A weed of riparian zones (banks of watercourses), disturbed closed forests, forest margins, open woodlands, roadsides, fence-lines, gardens and plantation crops in tropical and subtropical regions.


Thunbergia grandiflora is a long-lived (perennial), vigorous, climbing plant that can grow up to 15 m in height when supported by a host tree.

Younger stems are green, hairy (pubescent), and square in cross-section (quadrangular). The older climbing stems are quite thick when mature, and they usually turn brown in colour and become somewhat rounded in shape.

The oppositely arranged leaves are borne on hairy stalks (pubescent petioles) 4-12 cm long. These leaves are variable in shape (8-22 cm long and 3-15 cm wide) and may have broad heart-shaped (cordate) bases, be somewhat triangular in shape, or be roughly egg-shaped in outline with broad end at base (ovate). Their margins are also quite variable, and can range from being almost entire, to being irregularly toothed (crenated) or have several irregular, pointed lobes. The leaves are bright green in colour and somewhat hairy (pubescent).

The trumpet-shaped (tubular) flowers are borne in elongated clusters (racemes) on long, drooping (pendent) branches. They are large and showy (3-8 cm long and 6-8 cm across) with five pale blue, violet or mauve coloured petal lobes and a pale yellow or whitish coloured throat. Each flower is borne on a stalk (pedicel) 4-5 cm long and has two leafy bracts (bracteoles) at its base. These bracts (15-40 mm long and 10-20 mm wide) are oblong or ovate and have pointed tips (acuminate apices). The flowers also have hairy (pubescent) sepals that are fused together and reduced to a ring-like structure (calyx tube) that is greenish-coloured and may sometimes be streaked with purple or red. Flowering occurs throughout the year, in the plants around Nairobi.

The fruit is a capsule with a rounded (spherical) base (about 18 mm long and 13 mm across) and a long tapered beak (2-5 cm long and about 7 mm wide). These fruits are only produced in the warmer climates. The large, flattened (compressed), seeds (up to 10 mm across) are smooth on one side and warty on the other side. Seeds (5-10mm wide) contained in seed pods.

Reproduction and dispersal

Thunbergia grandiflora reproduces via seed. Seeds in pods are catapulted several metres when the pod splits.(but fruit are only produced in warmer climates). T. grandiflora is also capable of regenerating from stem fragments or portions of the tuberous roots and vegetatively by stolons. Dispersal of the disseminules may be by stem and tuber pieces carried by water or in dumped garden waste. The tuberous roots may also be spread during soil moving activities (e.g. roadworks) and by flood waters.

It is widely cultivated as an ornamental and hedge plant.

Similar species

Thunbergia grandiflora is not similar, but is related to other Thunbergia species among them Thunbergia alata (black-eyed Susan), Thunbergia battiscombei and Thunbergia fasciculata.

It is also similar to Thunbergia laurifolia (laurel clock vine) and quite similar to Thunbergia fragrans (fragrant thunbergia) and Thunbergia arnhemica all of which are exotic to the region.

T. grandiflora can be more easily distinguished from T. alata by the conspicuous yellow flowers which are much smaller.

Economic and other uses

Thunbergia grandiflora can be used as a medicinal plant, a green manure, for poles, hedges and for fuelwood. It is widely grown as a garden ornamental and wall covering in Kenya.

Environmental and other impacts

Thunbergia grandiflora has an extensive tuberous root system can be weigh up to 70kg. The root system persistently sprouts from its many buds when cut back or pruned. Tubers can damage river banks, paths, fences and building foundations. It is a vigorous climber and can smother vegetation up to 12 metres above ground, reducing light levels for lower vegetation. The weight of the stems can kill trees during infestations. Although it is not currently regarded as a major threat in Kenya, Tanzania and Uganda, it is an important weed in Australia where is can infest agricultural lands and in some conservation areas can establish 100 per cent ground cover and exclude all native vegetation.

T. grandiflora has been included in the Global Invasive Species Database (GISD 2010).


The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species. Some components of an integrated management approach are introduced below.

The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.

To control this plant, small plants can be dug out, but more established plants have extensive underground tubers that are difficult to remove from the ground completely and therefore removal has to be done repeatedly.

Spraying or painting cut stumps with herbicides such as glyphosate is an effective control method. When using any herbicide always read the label first and follow all instructions and safety requirements. If in doubt consult an expert.

The editors do not know of any biological control programmes targeted at this species.


Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.

Germplasm Resources Information Network (GRIN). National Germplasm Resources Laboratory, National Genetic Resources Program, Agricultural Research Service (ARS), United States Department of Agriculture (USDA), Beltsville, Maryland, USA. Accessed March 2011.

Global Compendium of Weeds. Hawaiian Ecosystems at Risk Project. Accessed March 2011.

Lazarides, M., Cowley, K. and Hohnen, P. (1997). CSIRO Handbook of Australian Weeds. CSIRO Publishing, Collingwood, Victoria.

USDA Plants Profile. Thunbergia grandiflora Roxb. Bengal trumpet. The Plants Database. National Plant Data Center, National Resources Conservation Service, United States Department of Agriculture, Baton Rouge, Louisiana, USA. Accessed March 2011.

Weber, E. (2003). Invasive Plant Species of the World: A Reference Guide to Environmental Weeds. CABI Publishing, Wallingford, UK.


Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat – UK.


This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) – Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).


BioNET-EAFRINET Regional Coordinator: [email protected]

blue thunbergia

Blue thunbergia (Thunbergia grandiflora) is very similar to laurel clock vine (Thunbergia laurifolia) and relatively similar to fragrant thunbergia (Thunbergia fragrans), black-eyed Susan (Thunbergia alata) and the native species Thunbergia arnhemica.Although laurel clock vine (Thunbergia laurifolia) is so similar to blue thunbergia (Thunbergia grandiflora) that the characters of these species almost overlap, it can usually be distinguished by the following differences: blue thunbergia (Thunbergia grandiflora) usually has relatively broad leaves bearing relatively large pointed lobes and/or toothed margins. It leaves are usually hairy (i.e. pubescent) and are borne on relatively long hairy stalks (4-12 cm long).laurel clock vine (Thunbergia laurifolia) usually has relatively narrow leaves that are almost entire or have shallowly lobed or toothed margins. Its leaves are hairless (i.e. glabrous) and are borne on relatively short stalks (usually less than 3 cm long). Blue thunbergia (Thunbergia grandiflora) can be more easily distinguished from the other species by the following differences: blue thunbergia (Thunbergia grandiflora) has large flowers (60-80 mm across) that are usually blue or purplish in colour (white in Thunbergia grandiflora ‘Alba’) with broad throats that are pale yellowish in Susan (Thunbergia alata) has relatively small flowers (25-40 mm across) that are usually orange (white in Thunbergia alata ‘Alba’) with conspicuous blackish coloured throats that are quite narrow.fragrant thunbergia (Thunbergia fragrans) has moderately large flowers (about 50 mm across) that are entirely white in colour and have a very narrow throat.Thunbergia arnhemica has moderately large flowers (about 50 mm across) that are entirely white in colour and are bell-shaped with a relatively broad throat.

Planting Sky Vine Seeds And Cuttings: How To Grow Sky Vine Plants

By Paola Tavoletti

Have you a passion for violet-blue flowers? Then, discover sky vine growing! What is a sky vine you ask? Read on to learn more about growing this charming landscape plant.

Sky Vine Growing

Sky vine (Thunbergia grandiflora), also commonly referred to as clock vine, a member of the tropical Acanthaceae family and is an evergreen in frost free climates, where it also produces fruits, but growth slows or stops in cool temperatures. It is hardy in Zones 8-11.

The clusters of its trumpet flowers will enrich your garden with the vibrant feel from India, its origin. Dramatic lavender-blue flowers on a backdrop of dark green heart-shaped leaves will light up your garden all summer, or all year long in tropical climates.

Sky vine growing is rewarding. The plant blooms profusely, and its stunning flowers make great cutting specimens for arrangements. This vine is ideal for covering a fence, pergola, large trellis or an arbor. It sends out long wandering tendrils, which can even grab onto a nearby tree branch, becoming an interesting focal point in the garden. It’s this growth habit which gives the plant its name as well.

One note of caution is that this woody-stemmed, twining evergreen can be invasive, as it can easily regenerate from stem fragments or portions of the tuberous roots.

Sky Vine Propagation

In addition to rooting from its stems, sky vine plants can be propagated by seeds, cuttings and layering.

Planting Sky Vine Seeds

Sky vine thunbergia can be grown from seed started indoors 6 weeks before the last spring frost date. Planting sky vine seeds is easy. Start by sowing two or three seeds in a small pot of fine textured potting soil, then place the pot in a bright, warm location and water regularly.

Once seedlings emerge and have grown large enough, choose a location in your garden with full sun to partial shade and rich organic soil. Install a trellis to support the vines. Plant the seedlings when the night-time temperature is above 50 degrees F. (10 C.). Water regularly.

Sky Vine Cuttings and Layering

For cuttings of sky vine plants, simply prune the young wood in spring and place the cuttings in small pots filled with sandy loam or soilless growing medium. They will root readily and need no additional help like rooting hormone.

To propagate by layering, you bend a low-growing branch until it touches the ground. Scrape the branch where it touches the ground, then secure the scraped area to the ground with bent wires. The branch will develop roots from the wounded bark, after which it is then severed from the parent plant.

How to Grow Sky Vine Plants

Sky vine plants grow best in rich organic soil, moderately moist and well drained with acidic, alkaline, or neutral pH levels. They can also thrive in pots.

This vigorous vine grows in full sun, with a southern exposure, but stays greener and prettier with a little shade protection from the blazing afternoon sunshine, especially in warmer climates.

Water the plant when the soil is dry, and fertilize in spring and fall with a granular fertilizer.

Prune after the blooming cycle is over to encourage a quick re-sprout, and prune again in late summer. When winter comes close, mulch the roots with pine needles or other organic material.

Spider mites, whiteflies, and edge burn may damage the plant.

Learning how to grow sky vine plants will give your green space a touch of diversity and fascination.

A fine vine is the sky vine

By Ralph E. Mitchell

It is good to know the botanical name of a plant as the common name can be varied and confusing. For instance, the plant known as Thunbergia grandiflora, is commonly known as the Bengal clockvine, Bengal trumpet, blue sky flower, blue Thunbergia, blue trumpet vine, clock vine, sky flower and sky vine. For our purposes, let’s just call it the sky vine. A fast-growing and beautiful flowering vine, the sky vine has abundant lavender-blue flowers that will mark your landscape as a must-see for passersby. Have your heard of this plant?

The sky vine is probably more common than you think as it often shows up in yards with a fence that needs covering. Twining rapidly during the growing season, but slowing to a near standstill during the cooler part of the year, the sky vine makes rampant and vigorous growth for quick coverage of arbors, trellises, and fences. Growing in sun or part- shade, it is known to do well even with some shade especially during the heat of the summer. The heart-shaped leaves are dark-green in color and less than two-inches wide. The jewels of this vine are the sky-blue to lavender-blue flowers measuring up to three inches long with whitish throats that develop in attractive clusters. While sky-blue is the most common color, there is also a white-flowering cultivar available.

Besides using the sky vine on a trellis or fence, also consider using it as a container plant, as a screen or even positioned to spill and cascade over a wall. There are also suggestions of using the sky vine in combination with cannas, ferns and around or about water gardens.

The sky vine is hardy in our area, but can be frost damaged with quick recovery being the norm. It is incredibly easy to propagate from cuttings or air-layering. The sky vine will benefit from regular watering and may require some pruning to keep it in bounds. Its aggressive nature can make it a bit invasive, so manage this plant to prevent its escape.

The sky vine is an incredibly beautiful vine that will provide a wall of color and texture for that special vertical space in your yard. For more information on all types of flowering vines suitable for our area, please call our Master Gardener volunteers on the Plant Lifeline on Mondays, Wednesdays and Fridays from 1 to 4 pm at 764-4340 for gardening help and insight into their role as an Extension volunteer. Don’t forget to visit our other County Plant Clinics in the area. Please check this link for a complete list of site locations, dates and times – .

by spacemonkey

Posted: March 19, 2018

Category: Agriculture, Florida-Friendly Landscaping, Home Landscapes

Tags: Bengal clockvine, Bengal trumpet, blue sky flower, blue Thunbergia, blue trumpet vine, clock vine, fast-growing, flowering vine, sky flower, sky vine

Thunbergia Mysorensis Plant – Mysore Trumpet Vine, Indian Clock Vine

Common name: Mysore Clock Vine, Dolls shoes, Brick and butter vine

Botanical name: Thunbergia mysorensis Family: Acanthaceae (Barleria family)

Synonyms: Hexacentris mysorensis

Thunbergia mysorensis is a stunning, vigorous vine from southern India where it climbs through trees in tropical montane forests. It has become naturalized in Mediterranean climates and elsewhere due to its popularity as an ornamental plant.

The generic name commemorates the Swedish botanist Carl Peter Thunberg, one of Carl Linnaeus’s pupils and a prolific collector of Asian plants. The species epithet is a reference to the city of Mysore (today Mysuru) in the Indian state of Karnataka.

Thunbergia mysorensis has pendulous racemes of striking, red and yellow inflorescences. Each flower is up to five centimeters long with showy red bracts. The tubular flowers are bilaterally symmetrical, consisting of five fused petals. The petal tips are colored red which are reflexed to expose the yellow throat, the large stamens, and feathered stigmas.

A great number of growers from around the world have chosen this one, and rightly so. In flower almost every day of the year, a mature vine bears hundreds of 3″ yellow and rust red flowers in spectacularly long hanging chains. The vine often reaches 20 feet (6 metres). Oppositely arranged ovate-lancelike leaves are 5-6 inches long, and handsome dark glossy green. Flowers are large, in long pendulous interrupted racemes. The plant is more delicate in appearance than its blue flowered cousins. The plant is a popular garden item because of its attractiveness to hummingbirds. This vine is shy of seeding and has to be propagated by layering. Flowers in the cold season.

In its native range, Thunbergia mysorensis is pollinated by sunbirds. Where it has naturalized in the Americas it’s abundant nectar is a source of food for hummingbirds. As they feed, the heads of visiting birds become dusted in pollen, which is transferred to other flowers. Pollination is completed because of the position of the anthers and the stigmas, held against the inner and upper surface of the reflexed corolla.

In temperate zones, Thunbergia mysorensis is a conservatory or greenhouse plant. It requires a winter minimum of 12 degrees Celsius in full sun or partial shade. The stems twine clock-wise and as they mature this produces an ornamental effect, similar to Wisteria floribunda. Pruning is best completed in spring by thinning the crowded stems. It will produce single flowers in the axils of the leaves, but to produce its striking pendulous racemes, this climber requires a run of several meters. These inflorescences are often more than 30 cm in length and create a dramatic display. Thunbergia mysorensis originates from a monsoon climate and so requires plenty of water over summer.

Thunbergia mysorensis

Category: Climbers, Creepers & Vines Family: Acanthaceae or Crossandra or Thunbergia family Light: Sun growing, Semi shade Water: Normal, Can tolerate more Primarily grown for: Flowers Flowering season: January, February, March Flower or Inflorescence color: Various colored flowers available viz., Yellow, Orange, Red Foliage color: Green Plant Height or length: 6 to 8 meters Plant Form: Climbing or growing on support Special Character:

  • Indigenous (native to India)
  • Can grow on trellis or chain link fencing
  • Attracts birds
  • Attracts bees
  • Recommended for creating shade
  • Must have for Farm house or big gardens

Generally available in India in quantities of: Over hundreds Plant Description: – What a beautiful climber! It is impossible to forget a plant in full bloom.
– Fron South India in the Wetern Ghats.
– A climbing shrub with long slender branches.
– Leaves opposite, elliptic or oblong lanceolate, 10 – 15 cm long, 3 – 5 cm broad.
– Flowers on long, pendulous raceme.
– Corolla tube 4.5 cm long, purple, enclosed by spathe like bract.
– 4 lobed limb yellow or maroon spotted with yellow.
– Upper lip erect, concave with reflexed side lobes lower lip 3 unequal spreading lobes. 5 cm across. Growing tips: – Plants are best trained over gazebos, pergolas, arches or frame support to allow to large racemes to hang down and show.
– Avoid planting on fences – as the flowers do not show off well.
– Plants prefer well drained acidic soils.
– Avoid vary hot and dry weather. Plants can partially shaded if required. Generally available with us at: Tukai Exotics, The Enchanted Gardens

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