Thunbergia Species, Bengal Clock Vine, Blue Sky Vine

Thunbergia grandiflora

Family: Acanthaceae (ah-kanth-AY-see-ee) (Info)
Genus: Thunbergia (thun-BER-jee-uh) (Info)
Species: grandiflora (gran-dih-FLOR-uh) (Info)
Synonym:Flemingia grandiflora
Synonym:Pleuremidis grandiflora
Synonym:Thunbergia adenophora
Synonym:Thunbergia chinensis
Synonym:Thunbergia cordifolia


Tropicals and Tender Perennials

Vines and Climbers

Water Requirements:

Requires consistently moist soil; do not let dry out between waterings

Sun Exposure:

Sun to Partial Shade




Foliage Color:



15-20 ft. (4.7-6 m)


15-18 in. (38-45 cm)


USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

USDA Zone 9a: to -6.6 C (20 F)

USDA Zone 9b: to -3.8 C (25 F)

USDA Zone 10a: to -1.1 C (30 F)

USDA Zone 10b: to 1.7 C (35 F)

USDA Zone 11: above 4.5 C (40 F)

Where to Grow:

Grow outdoors year-round in hardiness zone

Can be grown as an annual

Suitable for growing in containers



Bloom Color:

Light Blue


White/Near White

Bloom Characteristics:

This plant is attractive to bees, butterflies and/or birds

Flowers are showy

Bloom Size:


Bloom Time:

Mid Summer

Late Summer/Early Fall

Other details:

May be a noxious weed or invasive

Soil pH requirements:

6.1 to 6.5 (mildly acidic)

6.6 to 7.5 (neutral)

7.6 to 7.8 (mildly alkaline)

Patent Information:


Propagation Methods:

By dividing the rootball

From leaf cuttings

From herbaceous stem cuttings

Seed Collecting:

Allow seedheads to dry on plants; remove and collect seeds

Properly cleaned, seed can be successfully stored


This plant is said to grow outdoors in the following regions:

Montevallo, Alabama

Vincent, Alabama

Glendale, Arizona

Alameda, California

Elk Grove, California

Encinitas, California

Fallbrook, California(5 reports)

Hughson, California

San Clemente, California

San Leandro, California

Santa Barbara, California

Stockton, California

Walnut Creek, California

Bartow, Florida

Boca Raton, Florida(2 reports)

Bokeelia, Florida

Casselberry, Florida

Clermont, Florida

Cottondale, Florida

Dade City, Florida

Debary, Florida

Deltona, Florida

Fort Lauderdale, Florida(2 reports)

Fort Mc Coy, Florida

Fort Pierce, Florida

Gainesville, Florida(2 reports)

Gulf Breeze, Florida

Holiday, Florida

Hollywood, Florida

Interlachen, Florida

Jacksonville, Florida(2 reports)

Key Largo, Florida

Lake Mary, Florida

Lakeland, Florida

Merritt Island, Florida(2 reports)

Miami, Florida

Morriston, Florida

Mulberry, Florida

Niceville, Florida

Ocala, Florida

Ocoee, Florida

Orange Park, Florida

Pensacola, Florida

Plant City, Florida

Pompano Beach, Florida

Port Charlotte, Florida

Rotonda West, Florida

Sarasota, Florida

Satellite Beach, Florida

Starke, Florida

Vero Beach, Florida

Wellborn, Florida

West Palm Beach, Florida(2 reports)

Yulee, Florida(2 reports)

Zephyrhills, Florida

Columbus, Georgia

Guyton, Georgia

Kurtistown, Hawaii

Baton Rouge, Louisiana

Bossier City, Louisiana

French Settlement, Louisiana

Gonzales, Louisiana

Lafayette, Louisiana(2 reports)

Lake Charles, Louisiana

Mandeville, Louisiana

Thibodaux, Louisiana

Carriere, Mississippi

Florence, Mississippi

Gautier, Mississippi

Natchez, Mississippi

Saucier, Mississippi

Brookline, New Hampshire

Averill Park, New York

Conway, South Carolina

Sumter, South Carolina

Germantown, Tennessee

Austin, Texas(3 reports)

Boerne, Texas

Brazoria, Texas

Bryan, Texas

College Station, Texas

Dickinson, Texas

Freeport, Texas

Galveston, Texas

Houston, Texas

Humble, Texas

Jacksonville, Texas

Magnolia, Texas

New Waverly, Texas

Plano, Texas

Richmond, Texas

Rosenberg, Texas

San Antonio, Texas(2 reports)

Santa Fe, Texas

Spicewood, Texas

Tyler, Texas

Vidor, Texas

St John, Virgin Islands

Spangle, Washington

show all

Gardeners' Notes:


On Nov 7, 2020, CelesteHutch from Yulee, FL wrote:

I purchased my second blue sky vine early this spring. I had one about 20 years ago and it grew along a fence for about 40 feet each year and bloomed profusely. I loved it, one of my favorites. This year in late winter I found another one, there hard to find in Florida. It grew like crazy but didn't flower until about mid summer. I noticed that it bloomed on the sun side of the vine. It's early November and it is producing more and more blooms on the side. We planted it at the corner of our house along the downspout from the gutters. We've had a lot of rain in Northeast Florida this year. Am now trying to plant some of its seeds as I have friends who would like one.


On Sep 15, 2020, SlenderHope from Gainesville, FL wrote:

My husband bought this plant for me as a birthday present That was 10-15 years ago. We live in zone 9a and for me, this plant has always died back in the winter and then come galloping back in the spring. I've kept it in a pot for all of that time, but am considering moving it to a bed. Mine (which I believe is the thunbergia erecta, or King's Mantle) seems to have almost a vining habit although these stems are thick and not very flexible. I'm going to be transferring it from the pot to a bed in the spring because I've seen it used around here as a bedding plant with great success.


On Sep 8, 2018, Rests from Bryan, TX wrote:

As with other vines, I was advised that this would take over the yard like crazy. This has been a true disappointment. It started out growing like crazy as long as we got lots and lots of rain. When the rain stopped and started using city water, this vine started cratering. Bryan water has a lot of sodium. I think I will end up pulling it all up and throwing it in the trash. Not worth the high price that it costs to buy it. Was hoping for a real invasive vine.

May 2019

Decided to give it another chance. It died down almost down to the ground. The little stem is green, but it has not tried to sprout. It is in a pot. If it doesn't sprout in the next couple of weeks, I will throw it in the trash. Beautiful vine, but a real dud in Central Texas... read more


On Aug 26, 2017, tpeterson from Lakeville, MA wrote:

I have had this in a pot all summer and here it is, the end of August and still no blooms.


On Sep 4, 2016, coriaceous from ROSLINDALE, MA wrote:

In tropical to semitropical climates, this is a woody, evergreen, twining liana that can climb 60' and bloom year-round. In warm temperate climates, it blooms from late summer into fall. Very vigorous and floriferous here in Ajijic, Jalisco, Mexico, and deservedly popular.

It has a tuberous root system with a deep taproot. This makes it drought tolerant once established, though it performs best with lots of water in summer and kept fairly dry in winter.

It's unusual in its tolerance for shade.

The Royal Horticultural Society has given it its coveted Award of Garden Merit.

This twiner can smother large trees. Best planted where it can climb a fence, wall, pergola, or other structure.

It has become a serious environme... read more


On Jun 17, 2015, jidanni from Dongshi Taichung,
Taiwan (Zone 11) wrote:

Watch out, Thunbergia grandiflora's massive tuber network may eventually get underneath your house and start lifting it up! "T. grandiflora has an extensive tuberous root system, which can damage ... building foundations":


On Oct 30, 2014, vossner from East Texas,
United States (Zone 8a) wrote:

Mine has done poorly b/c of insufficient moisture. It's inground, part shade, growing along an oak for support. I won't move it. If it lives, it lives. Not fond of vines as a rule, but love the beautiful blue flowers I've seen in garden tours.


On Aug 11, 2014, burien_gardener from Burien (SW Seattle), WA (Zone 8b) wrote:

This vine will grow in Seattle area (Z 8) but requires many days of high temps to bloom. Not often in Seattle (2014 being an exception).


On Mar 10, 2014, behunkas from Venice, FL wrote:

i have tentatively identified this plant as one growing in semi-shade on fence outside office building in venice(island)florida. but, it is blooming now, in early march. no one in the office building can identify the plant, but all admire its beautiful lavender bloom. is there a vine guru out there who can confirm my identification, or offer a suggestion re what this vine might be?


On Mar 22, 2013, TexasDollie from Dewey, AZ (Zone 7a) wrote:

Got a start of this at our MG class, trained it over the shady-ish arbor of the veggie garden gate. Trained is not the word, more like...stood back and watched it eat the arbor. Not much in the way of flowers the first couple of years, but last year it was covered in them. We're moving, but I have a start of it to take with me.


On Apr 24, 2012, Nanciii from Bossier City, LA wrote:

I have had the Blue Sky flower for years comes back every year and its gorgeous, it loves to take over my gate, some years have been better than others as far as blooming last yr with the heat vine was fine blooms pretty minimal. Mine blooms when the heat of the summer get here late june Ealy July. One of my absolute favorites.


On Jul 17, 2011, dirtyshovel from Lake Mary, FL (Zone 9b) wrote:

Planted in spring and it has overtaken a 6 ft fence, but few flowers. Maybe too much fertilizer? Neighbor's up the street
is loaded with blooms but is several years old.


On Jul 4, 2010, Aquarius247 from Lake Alfred, FL wrote:

I've grown this vine in my central Florida yard for 3 years. I never knew its name until now. This past winter it froze to the ground, but now it is growning up an old clothes line post and line. It flowers from late June to late winter. The only problem I've encountered was from aphids. I did grow a second vine from a cutting after rooting it in water. The flowers look like Morning Glory but last for days.


On Jul 26, 2009, fullsun007 from Gainesville, FL wrote:

I have had this fine growing in my yard for several years and it never ceases to disappoint. I have limited space in my yard, so planted my blue sky vine at the base of my Japanese Magnolia which flowers here in zone 8B in early spring but after which provides little color the rest of the season. So I let the tree provide the frame for the vine to grow up and by mid summer have those beautiful flowers appearing all over the tree. I have not had trouble with seeds and volunteers.


On Jul 13, 2009, khabbab from lahore,
Pakistan (Zone 10b) wrote:

In lahore pakistan, this vine blooms late in summer till start winter. Blue blooms are very pretty. It responds good to container culture. It is fast growing vine needs fertilizer in growing season. There is another yellow flower variety called black eyed Susan but it has smaller flowers than blue ones.


On May 5, 2009, SierraTigerLily from Boca Raton, FL (Zone 10b) wrote:

Constant bloomer, grown with roots in the shade and protected from noonday sun. I give it tropical fertilizer and it thanks me by shooting out new branches of blooms a week or two later. Although I hack it back every few months, this twining vine shows no potential for "escape" four years after planting. Its root area is exactly the same as when I first put it in the ground. I find it easy to keep the plant contained on one arch. All visitors to the garden stop and touch the flowers.


On Jan 29, 2009, WillowWasp from Jones Creek, TX (Zone 9a) wrote:

This plant is a joy to keep and so beautiful to look at. I wish I had more and I will try and do cuttings and see how well they do this spring. I am really impressed with her and I love all the beautiful flowers from early spring to almost winter.


On Dec 30, 2007, wkeen27913 from Glendale, AZ (Zone 9b) wrote:

Great plant for phoenix and area. Loves the sun but also loves water. Still blooming at Christmas and has survived a few minor frosts. Do not plant where you dont want it to climb!


On Sep 29, 2007, lsander153 from Pittsburgh, PA wrote:

I planted this in a pot from a small cutting last May. I put the pot next to an 8' trellis in a sunny part of my garden. It bloomed pretty well at the start, then grew profusely up the trellis, but with no blooms. There are now (September) two flowers at the top, and several buds. I plan to cut it back and bring the pot in over the winter. I'd like to know how to get more blooms.


On Apr 19, 2007, Lily_love from Central, AL (Zone 7b) wrote:

I would recommend these vines, beautiful, rare blue flowers when other colors fade toward the end of the seasons. Though, treating them as hebacious perennials, this does faithfully bloom every year. I would avoid having this vine tangle with other evergreen vines since we have to pull the spent vines off in winter.

March 20011 update; severe winter killed my vines last year. I'm working on replacing the vines.


On May 16, 2006, ANGELONA from 00987,
Venezuela wrote:

Hello. I dont speak spanish well. I cant seed this plant... i have cuttings but dont grow. This plant have seeds?

Someone explain me please how I can reproduce thunbergia grandiflora?



On Nov 10, 2005, sunriselmi from Hughson, CA wrote:

i saw this in an arboretum in canada. then found in a local HARDWARE store! 3 years, comes back every year from frost to 15 feet, flowers late summer thru fall. pest free, vigorous, beautiful flowers. no doubt division is easiest and fastest propagation.


On Jul 12, 2005, dmaroni from Chapel Hill, NC wrote:

I grow this in a pot, outdoors in the summer, then cut it back and overwinter it in a greenhouse. It grows vigorously but produces only few of its gorgeous flowers only late in the season.

I am troubled by all of the discussions of its invasiveness in Australia and Hawaii **and** Florida
where it is considered a real nuisance. I'm reminded of kudzu which also has pretty flowers and, what's more, incredible grape-soda fragrance: this beast is marching across some parts of the NC landscape and it has almost devoured SC and GA. It would be horrible if like that were to happen with Thunbergia, so those of you who have it survive over winter should be especially careful that it doesn't get away from you!


On Nov 10, 2004, CaptMicha from Brookeville, MD (Zone 7a) wrote:

I didn't appreciate the beauty of this plant until I saw one in person. The large blue heavenly blooms are incredible! And they last for days which is always a bonus for me.

I find it very easy to flower because mine is flowering inside and is covered in buds. I don't give it any special care except for a sunny window, something to climb on and water about once a week. It's in a quart container at about 72 degrees.

The only problem I encountered with it is an aphid infestation which was easily taken care of. I can't wait to see how this plant will do outside once it warms up again.


On Jul 10, 2004, zachcap from Cortez, FL wrote:

I need some info regarding feeding practices to encourage bllooms on a thunbergia vine in SW Fla. Any suggestions?


On Jun 26, 2004, DPalacios from Miami, FL wrote:

This plant is lush and hardy. It has grown about two feet since I planted it only four months ago. The problem is that it is still not flowering. It was flowering when I bought it. I am using time release fertilizer, but still no luck. Any feedback?


On Jun 15, 2004, Wingnut from Spicewood, TX (Zone 8b) wrote:

GORGEOUS vine!!! Roots easily from cuttings, though it takes a while. As long as they're green DON'T throw them out! Give them time, even months. They'll root.


On May 19, 2004, urbanite from Houston, TX wrote:

Grows well in Houston, TX


On Mar 13, 2004, crisee44 from Morriston, FL wrote:

I bought this from a local plant distributor here in Levy Co Fl.
I planted two plants about 8 feet apart in front of my deck and they completely covered the railings (22' long) in the first season.
The flowers came in the first yr too, and were absolutely beautiful and so profuse.
It has warmed up here in Central Fl and last week I found the plant already growing 44" up my deck. There area several shooters on the ground and I cut, dipped them in rooting compound and transplanted them in several other areas. One week later, they are still doing great. Can't wait to see how the cutting do this yr.


On Nov 22, 2003, allencpa56 from Moss Point, MS (Zone 9a) wrote:

I would like to say this is the best plant site I have visited. I came here looking for a plant that came up in my yard and started running everwhere. Everyone wanted to know what it was. I had no idea until I came here. This is a very helpful site. the plant is a bengal clock vine, blue sky vine.It came up beside a honeysuckle vine i had planted to run around ny porch. Can not even see the honeysuckle.Thanks for a wonderful site.


On Nov 11, 2003, chrislyn from La Porte, TX (Zone 9a) wrote:

I have had this vine growing in my backyard for about 2 years now. It is beautiful, fast growing and no signs of pest problems. I strongly recommend it.


On Jun 23, 2003, docturf from Conway, SC (Zone 8b) wrote:

This Thunbergia species does very well in the Coastal region of South Carolina and has survived temperatures as low as 15 F. No pests have been observed after more than 9 years of growth. If a mild winter takes place, the vine will continue to grow actively, although much less rapidly.


On Jun 22, 2003, amelia98 from Brookline, NH wrote:

Bought 2 or 3 years ago as a houseplant for those gorgeous flowers, it turned out to be infested with bugs and was tossed out the back door. I planted it next to the house not expecting it to survive the harsh winters of NH. The ants and lady bugs are taking very good care of it's bug problem and it's about to reach the top of the second story of my house. Prolific growth but not uncontrollable. Unfortunately, no sign of any flowers yet.


On Jan 21, 2003, Schmetterling from Louisville, KY (Zone 6a) wrote:

The tubular flowers of Thunbergia are a little deeper, about 3" long, and are borne in clusters.

The most commonly seen varieties are sky blue to light violet although there is a white flowered type as well. Leaves are leathery and have a distinctive, elongated heart shape. It is one of the most free flowering vines for shade in the South and is underused due to lack of distribution.

Growth slows or stops in cool temperatures, and the top is killed to the ground after a freeze. In frost-free climates, it is evergreen.


On Sep 4, 2002, tiG from Newnan, GA (Zone 8a) wrote:

Fast growing very pretty vine. The flower is one of the most beautiful I've seen. Haven't seen any bugs on this plant all summer, and have had no problems at all with it.
Will root from the petiole, takes a while, but is proven successful.