Plant of the Month – October, 2007

At a glance
Latin Name: Thunbergia battiscombei
Common Name: blue glory vine, blue clock vine, blue boy
Family: Acanthaceae (Acanthus)
Origin: Tropical Africa
Plant Type: herbaceous perennial scrambler

Flowers: 2-inch, pure blue trumpets with a yellow throat
Foliage: Bright green simple leaves
Mature height: 4-6 feet
Hardiness: Zones 7-11
Soil: Well-drained
Exposure: Full sun to afternoon shade
Water usage: Medium
Sources: Mail-order or local nurseries

About 15 years ago, I was working at a wholesale nursery in Dallas, and while I was loading plants into the back of a customer’s station wagon I spied a plant I’d never seen before. This particular customer had a knack for finding neat and new plants, so he eagerly dug it out from behind the carload of plants to show me his latest find. Dangling before my eyes was a hanging basket filled to overflowing with lush, tropical foliage punctuated with the most incredible blue flowers. I think he saw the lust in my eyes, or maybe it was the fact that I bluntly mentioned that he had two of the beauties – either way, he gifted me with that plant.

Needless to say, I immediately hit the references searching for its name. Since it was in a hanging basket, I assumed it was a tropical groundcover or vine. I discovered the plant in question was Thunbergia battiscombei, or blue clock vine, related to black-eyed susan vine (T. alata) and blue sky vine (T. grandiflora), both of which are annuals in my Zone 7 to 8 garden.

T. battiscombei has incredible, deep-blue flowers, without any of those violet or purple tones that are so commonly called blue. In the middle of the 2-inch-wide flowers is a small yellow throat that makes the blue “pop” even more. Foliage is a deep, glossy green and makes the perfect backdrop for the flowers.

One thing I quickly discovered is this plant really isn’t a true vine or shrub – I’d call it more of a leaner. The stems tend to lay around and on top of whatever is nearby; they will not climb on their own. Now that I’ve become more acquainted with this plant I actually like this growth habit. It is perfect for growing on those wrought iron trellises in containers or winding through chain link fence. So what it needs a little extra help?

Also, it’s just the right size – not too large or too small. The stems will grow about 6 feet long at the most, so it stays just constrained enough that the flowers are level with your eyes, unlike many other vines that want to flower on top of your house or somewhere over in your neighbor’s yard.

Blue glory vine loves it warm – the hotter it is the more flowers it makes. I’ve found that it will grow in full sun to afternoon shade. Just remember, the more sun it is in, the more you’ll have to water it. It isn’t too picky about soil, but the richer the growing medium, the bigger the plant and the more flowers you’ll get. I’ve found it grows equally well in a container or in the ground. In fact, that first plant I received stayed in a 20-inch-square plastic pot on my back patio for nearly 9 years. Yes, I said 9 years! I didn’t have room to bring it in the first winter, and I never thought in a million years it would actually come back up the next spring. But, it did. For years.

Blue glory vine may be a little hard to find. Sorry, I can’t help that. Unfortunately, local nurseries and growers don’t consult me about what plants to buy and it just isn’t worth writing about plants you kind find EVERYWHERE. Gardening should be an adventure, not a process. So, break out your computer do some searching on Google, or visit your local nursery and beg them to hunt for it. I’ve seen wholesale growers listing it this year, so I know it’s available.

Oh, and by the way John M. if you’re reading this, thank you for that great plant and all the others you gave me over the years!

About the author: Jimmy Turner is the Director of Horticulture Research at the Dallas Arboretum, visit for more information on his trials. For more plant profiles by Jimmy, subscribe to Neil Sperry’s GARDENS Magazine.

New Hardy Palm and Tropical Collection is open!

Visit the new Hardy Palm and Tropical Collection, a unique centerpiece behind the Water Walls in the Lay Ornamental Garden, giving a beautiful background to the most popular wedding site at the Arboretum.

The one-acre collection is the brainchild of Jimmy Turner, Director of Research at the Arboretum, and Tony Cerbone, palm expert and club member. The new plant collection consists of more than two dozen varieties of cold hardy palms that will prosper in the Dallas climate. Also included in the collection are dozens of tropical plants such as ginger, oleander, cestrum, hardy bananas, crinums, bamboo and other hardy tropical-style plants. These plants are, for the most part, winter hardy and will provide a distinctive landscape style for homeowners interested in a fresh look in their gardens.

Groundbreaking for the project took place two years ago. The design includes moss boulders and stone pathways, designed by Landscape architect Johnette Taylor, President of Roundtree Landscape. The First Men’s Garden Club of Dallasraised funds for this project from the sales of their hit gardening calendar, “The Men of the First Men’s Garden Club of Dallas.”

The collection also incorporates areas for bamboo trials, hardy bananas, hardy gingers, crinums, cestrum and other “tropical” style plants that are adaptable to the Zone 7 to 8 garden. The Hardy Palm and Tropical Collection will also be used as part of the Arboretum’s ongoing plant trials. The Arboretum lies on the cusp of zones 7 and 8, experiencing extremes of heat and cold. Periodic ice storms and variable winter temperatures will help determine hardiness of the palms and tropical plants for future landscape use in these zones. Plants will be evaluated for beauty, winter hardiness, growth rate and adaptability to our area. This information will be available via the plant trials Web site:

Posted by Neil Sperry
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