What Can Bloom in this Heat?

By Sally G. Miller (sallyg)
July 7, 2009

A trip to San Antonio Texas taught me a lot of Southwest history, but it left me one burning question - how can anything actually thrive and bloom in this South Texas heat? Here's a “show and tell” about several heat loving, bright-blooming plants that I saw during my visit. Any one is worth trying in your hot zone 8-plus yard or your less-than- zone 8 pots or hanging baskets.

(Editor's Note:  This article was originally published on August 6, 2008.)

Thumnail photo- Mission San Jose church dome, San Antonio, TX

Brown grass crunched hard underfoot. Hot sun blazed down on our shoulders. It doesn't take long to feel ‘wilted' at Mission San Jose on a typical late June day. But there, and in landscapes and roadsides around South Texas, were plenty of flowers looking totally unfazed by this dry heat. Good digital pictures, and friendly fellow gardeners at DG's Plant and Tree Identification Forum, were the easy route to learning names for the plants I saw. And when I started my research, I found out somebody else has been interested in heat loving flora. The Aggie Horticulture people at Texas A & M University operate a "Texas Superstar^TM" evaluation process for finding tough, beautiful landscape choices for Texas homeowners. (Find out more about it in Tamara Galbraith's article, Welcome the New Texas SuperStars^TM.) And who can use "Texas" and "flowers" in the same paragraph without the Lady Bird Johnson Wildflower Center coming to mind? Let me show what I learned in researching a few of the plants I saw.

At the Mission San Jose, I found a large bush with glossy green leaves and clusters of bright lemony yellow flowers. A fellow Dave's Gardener supplied the name; actually, many names. Call it Yellow Elder (for it's elderberry-like leaves I would guess), Trumpet Bush (for the trumpet shaped flowers), Yellow Bells (blooms are a pure sunny yellow), Ginger-Thomas, or Esperanza, or more technically Tecoma stans. It's a better-behaved relative of Trumpet Creeper, which is familiar to me on the East Coast. Esperanza gets rave reviews in Dave's Garden's Plantfiles. Growers say it's a carefree, no-pest, heat loving, dependably blooming, viny bush. Hardy for zones 8 and up, this bush is such a crowd-pleaser that some zone 7 gardeners say they'll try to overwinter it. I have a hot south facing spot in my yard where I might try it too. If you want one of these, look for the cultivar "Gold Star ". That's the Texas Superstar^TM cultivar of choice.

Retreating from the heat, I strolled in the shade near the mill at the Mission. This perky blue bloom was peeking shyly up at me from under the split-rail fence. It's a Dwarf Katie type of Mexican Petunia, Ruellia brittoniana. I know how tough dry shade can be for a plant, but Ruellia apparently does not. This is another zone 8 rated perennial. Foot-tall herbaceous stems with long strappy leaves looked great in the dry shade. It‘ll bloom even better in the sun, and will respond to water and fertilizer too. (The original, non-dwarf Ruellia could get aggressive in a rich location.) I later saw masses of the pink-flowered "Bonita" cultivar Katie Mexican petunia in the gardens of The Alamo. The Texas A & M horticulturists rave about the widely adaptable, pest-free nature of this plant. Maybe this is the one I'll try first!

Mexican petunia planted under a tree and along a low stone wall, at the Alamo

We wandered later through the demonstration historic gardens and Master Gardeners garden, which are near the Tower of the Americas. I recognized a "friend" from a trip to southern California. Describing this amazing, complex blossom could take dozens, hundreds, (a thousand?) words- digital camera to the rescue. These four-foot stems topped with airy, eye-popping red/orange/yellow clusters of bloom are Caesalpinia pulcherrima. You could call it Red Bird of Paradise, Pride of Barbados, Dwarf Poinciana, Peacock Flower, or flamboyan-de-jardin flower; it's another flower with many names and many positive comments from Dave's Gardeners. This one too is a zone 8 rated tender perennial. Like the Esperanza and Mexican Petunia, it's widely grown across the South, as a shrub or perennial depending on local frost. It blooms all summer despite heat and dry soil. This Caesalpinia's qualities have earned it the Superstar^TM rating for 2008. 

Here's a lovely that I knew from an earlier, more humidly tropical, vacation. I just didn't know it could thrive in this dry Texas heat. Bougainvillea is the genus name and seems to be the common name of choice too. This tropical vine has been hybridized into quite a few cultivars and color choices. Hot pink is appropriately popular, but Bougainvilleas also come in reds, oranges, purples and whites. Some even have variegated leaves. Scroll down this page from Plantfiles and be amazed. Most gardeners enjoy this plant as a large permanent tropical vine, but it can be used as a hanging basket or potted plant in areas with cold winters. Bougainvillea is zone rated at 9 and above, so it is a bit more tender than the first three. It needs full sun and well drained soil. "Wet feet" seems to be its only weakness.

I'm taking creative license on this one. There are fruit which means there were flowers. The funny thing about this classic desert plant is- I already have one in my zone 7 yard in mild, Mid-Atlantic Maryland! Surprisingly, one Prickly Pear Opuntia species is native to the East Coast of the United States, despite our moist summers and frosty winters. My Maryland, zone 4-able specimen has lots of cousins, and all can take the heat. I didn't ask for a guess on the species of the one I photographed. There are many, and this lets you choose your Prickly Pear's mature height somewhere in the range from a few inches to over your head. By the way, if one of the pads happens to have been broken off and is laying on the sidewalk, well...it's incredibly easy to root. Just watch out for the spines and prickles!

I just wouldn't feel right if I didn't give you a picture of Prickly Pear flowers- here you go!

One last flower, looking no more exotic and no less cheerful than a standard sunflower, is this cucumberleaf sunflower (or beach sunflower), Helianthus debilis. Talk about well drained soil, I found these happy faces in the dunes of Padre Island, baking in the hot sun and bobbing in the sea breeze. Can you see the velvety fuzz on the leaves? That may explain the "cucumberleaf" part of the name (cucumber leaves are fuzzy.) It also helps the plant retain water. If I could ever be lucky enough afford a beach house, I'll plant beach sunflowers. The USDA plant profile (linked on the name above) shows it growing naturally along the Gulf and Atlantic coasts. They'll grow as an annual if I don't make it to Texas for my sandy dream retreat.

There are more flowers in Texas that I didn't get to explore. I can click my way through the Superstars^TM listing to learn more, or use the Lady Bird Johnson Wildflower Center website to teach me about the native beauties. I can browse the varieties in Plantfiles, to find a source for the plant or read fellow gardener's comments. I can not use heat as an excuse for a flowerless summer garden- although I may admire it from my air-conditioned window seat!

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Click here to read more about Southwest gardening in "Santa Fe, New Mexico and My Father's Garden" by Carrie Lamont 

Credits/ References

Prickly pear photo used by permission from Chantell (Thank you!) All other photos property of author.

Technical references, linked in the text of the article above :

Texas Superstars. Texas A and M University

Lady Bird Johnson Wildflower Center

Plant-care.com, for Bougainvilles care

USDA Plants Database

About Sally G. Miller   I grew up playing in the Maryland woods, and would still do it often if life allowed! Graduate of University of Maryland, my degree is in Agriculture. Gardens and natural areas give me endless opportunity for learning and wonder. Naturally (pun intended) my garden style leans towards the casual, and my cultural methods towards organic. I like to try new plants, and have "some of everything" in my indoor and outdoor gardens. Thanks go to my parents for passing along their love of gardening and nature, and my husband and kids for being patient when I get lost in the garden.

Helpful links   [ Mail this article | Print this article ] » Read articles about: Tropicals, Annual Flowers, Perennial Flowers, Heat-tolerant Plants, Caesalpina, Bougainvillea, Helianthus » Read more articles written by Sally G. Miller « Check out our past articles!

Discussion about this article:

Subject Topic Starter Replies Views Last Post Yellow Bells Sue78597 7 36 Jul 8, 2011 7:48 PM More Heat loving San Antonio plants wesley4 5 45 Jul 1, 2010 1:05 PM planting esperanza tgrammy 1 5 May 31, 2010 7:03 PM Great... Sharran 4 39 Jul 9, 2009 1:13 AM informative article Jan23 8 73 Jul 7, 2009 2:51 PM good phicks 4 31 Aug 11, 2008 9:45 PM

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