 |
|
By William Scheick |
If you spotted coral bells (Heuchera) in the wild, you might not quite notice them. They are low to the ground and usually (as if camouflaged) blend in with their shaded green woodland surroundings. Their wispy floral spikes might draw your attention in early spring, but probably only briefly since the blooms are small.
This description hardly suggests plants that would make their way into our gardens. It was even more unlikely that these plants would ever become highly prized by gardeners. But these mostly modest North American members of the Saxifrage family did, in fact, become appreciated after they captured the interest of hybridizers, especially (since the 1990s) Dan Heims, Dr. Charles Oliver, Parker Lewis Little and Thierry Delabroye.
For most of us in Texas, trying to grow these woodland perennials in the ground is likely to be frustrating. It can be and has been done, but baking sunlight, insufficient rain, inappropriate soils, desiccating wind and relentless heat work against our odds. Nonetheless, heucheras are now widely available at Texas nurseries, where Texans do indeed purchase them. Many Lone Star gardeners beat the odds by using pots packed with suitable fluffy soil enriched by compost and then, as needed, watered and moved to bright-shade settings.
IT’S ALL ABOUT FOLIAGE
Heucheras [properly pronounced HOY-ker-ahs, but commonly pronounced HYOU-ker-ahs] produce delicate flower spikes studded with tiny bells. The tall spikes of pink-to-red flowers — hummingbird magnets — of the Southwest native H. sanguinea (atypically requiring alkaline soil) are probably the best known. Even so, flowers are not what have spiked gardeners’ fascination with coral bells. For most gardeners, heuchera’s extraordinary colorful and patterned heart-shaped evergreen foliage steals the show.
Marketed coral bells are all about bright-shade foliage. In the wild, most heucheras are relatively drab. Hybridized cultivars are another story altogether. Their leaves exhibit an amazing diversity of leaf coloring and patterning. Some of this happened naturally because the 50 or so species of heuchera interbreed easily, resulting in bee-fostered hybrids. Today, however, plant breeders, rather than bees, account for most of the stunning retailed coral bells.
Subtleties of leaf coloration can emerge even after you bring a heuchera home. The plant’s foliage hue might change in response to seasonal variations in light and temperature. In my Central Texas experience, their leaf color tends to deepen during winter, whereas hue tends to fade in too much light and heat during summer. Too much water depletes color, too.
Winters are not a problem when growing heuchera hybrids in Texas. If the foliage gets tattered, it’s easily pruned back to foster new leafing in the spring. Clay is deadly, direct sunlight is deadly (even well north of our state) and heat can also be an issue. Most of these woodland perennials prefer cooler, more moderate climates than ours. As a result for you and me, there is often a certain amount of necessary home experimentation with different hybrids, which are definitely not equal in their adaptability to our plant-stressing conditions. Even so, I have found that if coral bells are cared for properly as evergreen potted plants in our Texas conditions, they don’t grow much overall, once mature, but generally endure as perennials for a few years. Otherwise, they function like annuals.
POTTING CORAL BELLS
“Heucheras are among the best perennials to grow in containers,” according to Dan Heims, founder of Terra Nova Nurseries in Oregon. Since they “are often denizens of small soil deposits in rock walls,” they are naturally adapted to “a confined life” in pots. In the wild, coral bells often thrive on steep slopes or in rocky crevices.
In the wild or at home, heucheras insist on excellent drainage and neutral to slightly acidic soil rich in organic matter. For container-raised coral bells, Heims has advised avoiding the peat-heavy potting soils typically available in retail outlets. Instead, combine peat (30 percent), bark (30 percent) and pumice (40 percent).
Water your coral bells, which respond well to Xeric treatment, only when their soil is dry. Average rainwater has the right amount of acidity for these perennials. Feed them rarely — at most with a slow-release 16-5-9 formula in roughly four-month intervals. Consult each selection’s label for shade requirements, which vary depending on the plant’s parentage. And position them for good air circulation to lessen the possibility of fungal infection.
Heims has also advised against burying a heuchera’s rosette crown — the spirally arranged leaves forming its central growing tip. Burying the crown would be a fatal error. Heuchera crowns often become woody and non-productive over time, too, which is why I mentioned earlier that coral bells can endure as perennials for a few years. Around three years, huecheras need to be divided and their rooted offsets (at the base of the crown) repotted if you wish to keep them.
“At the end of the second [growing] season,” hybridizer Dr. Charles Oliver has observed, “the offsets begin to make their own root systems, and by the end of the third season the whole clump can be dug up in early spring, most of the soil knocked off and the clump divided into pieces and replanted.”
HEDGING YOUR BET
To hedge your bet with coral bells, there’s this advice from Jimmy Turner, Senior Director of Gardens at the Dallas Arboretum and Botanical Gardens: Look for cultivars and hybrids of H. villosa, also known as hairy alumroot. This hardy, large-leafed and super-tough native of regions east of the Mississippi River loves shade, tolerates dryness, shares space with tree roots and companions well with many other plants, including hostas (another bright shade-lover). The rare flowers of hairy alumroot tend to be negligible, but the attractive whitish “fuzz” on its leaves and stems enables the plant to cope with our heat and humidity.
Turner’s trial-list of long-lasting (in-ground!) H. villosa cultivars includes ‘Brownies,’ ‘Caramel,’ ‘Citronelle,’ ‘Georgia Peach’ and ‘Mocha.’ A little lower on his list are ‘Mahogany,’ ‘Obsidian’ and ‘Southern Comfort.’ Other H. villosa cultivars you might try include ‘Molly Bush,’ ‘Bronze Wave,’ ‘Palace Purple,’ ‘Autumn Bride’ and ‘Dolce Key Lime Pie’ — altogether an ample sampling of coral bells that can put on a show in spite of our Texas heat.
Two more heuchera species known to do well in heat and humidity are H. pubescens and H. americana (a native of northeastern Texas). Look for ‘Garnett,’ ‘Bartram,’ ‘Dale’s Strain,’ ‘Plum Pudding,’ Green Spice’ and ‘Amethyst Mist,’ among others.
HEUCHERELLAS
Turner is also bullish about some heucherellas. Heucherellas result when heucheras are crossed with their close woodland relatives known as tiarellas. Tiarellas (foam flowers) produce showy small floral spikes. While there are only a few known species of tiarella — most are native to North America — the appealing possibilities in combining their attractive leaf shapes and heuchera’s colors are apparently infinite. As a bonus, heucherellas are sterile, which allows for more profuse and even repeat blooming.
Here’s an odd personal fact, though. In all of my years of haunting Central Texas plant nurseries, I have seen many heucheras — more each year — but only one heucherella selection. That recent selection is ‘Spotlight,’ which I would not recommend for most of us in Texas.
Some experts have found that heucherellas are fussier than heucheras. Dennis Carey and Tony Avent, at the famous Plant Delights Nursery in North Carolina, have reported that heucherellas “are generally less heat and cold tolerant than either parent.” Even so, Turner has praised them “as perfect plants for the high heat and humidity of Texas.”
Turner shouldn’t be misunderstood. He is referring specifically to heucherellas with H. villosa parentage, “which has added enough resistance to heat, drought, and humidity to make [them] able to handle even the extreme climate of Texas.”
Such cultivars as ‘Alabama Sunrise,’ ‘Tapestry’ and ‘Golden Zebra’ make Turner’s list of heucherella recommendations. He is particularly fond of ‘Sweet Tea’ with gorgeous bronze-hued foliage with burgundy veins.
