Any gardener who has lived in the South for long knows that we’re not really so concerned about how cold-hardy a plant is. We want to know how many seconds a plant will survive once the temperature reaches 103 and a nice, hot breeze is blowing.
For us, heat tolerance is much more important than cold tolerance because it’s hot a whole lot longer.
In the sage yet humble opinion of the Grumpy Gardener, no single person has done more to introduce great plants that won’t burst into flame once summer hits than Jimmy Turner. Jimmy is the Director of Horticultural Research at the Dallas Arboretum. And if you’ve ever spent a summer in Dallas, you know that summer in Baghdad ain’t much worse. (I’m talking heat here, not explosions.)
The Heat Is On
According to Jimmy, “[the Dallas Arboretum is] the premier site for heat tolerance and extreme climate plant testing in the U.S. On average, we get over 60 days over 100 degrees….and night temperatures are seldom below 85 during the summer.” Scorpions and centipedes love it, but plants? Not so much. Compounding the issue is the fact that summer days in Dallas are often clear, so cooling shade from clouds is a sometime thing.
Oh, and did I mention it’s often windy too? I remember spending 3 long days in Dallas when it was 103 degrees with a 25 MPH wind the whole time. It felt like walking into a blow dryer.
To find out which plants not only survive, but thrive under these conditions, Jimmy tests over 3,000 different selections of annuals, perennials, bulbs, tropicals, etc. each year on the 2-acre site. He awards those that past muster his coveted “Flame Proof” seal of approval.
Here are some of the recent winners. Hopefully, they’ll make their way to a garden center near you.
• Ageratum ‘Artist Alto’
• Angelonia ‘Serena’
• Hibiscus ‘Luna’
• Lantana ‘New Gold’
• Ornamental Pepper ‘Black Pearl’
• Salvia ‘Mystic Spires Blue’
• Vinca ‘Cora’
• Zinnia ‘Solcito’
Passing the Torch
One series of plants Jimmy is very enthusiastic about is the ‘Torch’ series of our native blanket flower (Gaillardia pulchella). They offer fully double flowers of yellow (‘Torch Yellow’) or red (‘Torch Red Embers’) from late spring through fall. Few plants are easier to grow. All they need is sun and good drainage. They grow 20 to 24 inches tall and seldom need water or fertilizer. They don’t get mildew, deer don’t eat them, and butterflies and hummingbirds love ‘em.
As with all blanket flowers, consider these short-lived perennials. They live at most for a couple of years, then bloom themselves to death. But they’re easy to grow from seed or you can buy new plants from the garden center. Try combining them with ‘New Gold’ lantana, another “Flame Proof” winner.
Plant of the Month
Every month, Jimmy names a “Plant of the Month” that his trials has proved superior and then emails info and photos about it to subscribers. If you want to subscribe, email him at email@example.com. Southern Living is proud to be a sponsor of the plant trials.