Heucheras That Beat the Heat

The efforts of several plant breeders over the past decade have inundated the market with scores of new varieties. The result: improved flower size and color, new foliage colors, patterns and leaf shapes.

Caramel Heuchera is a runner-up for the 2010 Perennial Plant of the Year award. 

Heucheras, commonly known as coral bells, have long been staples in shady perennial gardens, and with good reason. Their airy wands of hummingbird-attracting flowers bloom in late spring to early summer. They also make lovely cut flowers that I add to miniature bouquets of clove-scented dianthus, aquilegia, lady’s mantle (alchemilla), and Stachys ‘Hummelo’ — all of which bloom at the same time. The lobed, ornamental foliage forms neat, evergreen rosettes that look good almost all year, depending the climate. And another point in their favor, all the heucheras (pronounced HUE-ker-ah) species are native to North America.

The concentrated efforts of several plant breeders over the past decade have inundated the market with scores of new cultivars and hybrids between the species. Many have improved flower size and color, but the breeding focus has been mostly on new foliage colors and patterns and leaf shapes. Palace Purple, with deep maroon foliage, was the first heuchera I bought for my new shade garden in the early ’90s. Since then, I’ve added silvery Pewter Veil, Cinnabar Silver and Paris, chartreuse Lime Rickey deep-purple Obsidian and Amethyst Myst, and others with startling foliage.

Heucheras Climate

Most Heucheras perform best in cooler climates, such as my Zone 4-5 garden, and none grow well in full sun. Hot, humid summers especially take a toll on these plants. But, recently, breeders have accepted this as a challenge to be overcome. Heuchera villosa, a species native to the southeast, has made its way into breeding programs, resulting in a number of beautiful new cultivars with greater heat and humidity tolerance.

French hybridizer Thierry Delabroye introduced the H. villosa hybrid Caramel in 2006 and it became an instant sensation. A runner up for 2010 Perennial Plant of the Year, the soft coppery foliage is accented by pink to red undersides. What’s more, it holds its own against the humid dog days of late summer. In cooler climates, it tolerates more sun than most other Heuchera cultivars, too. Delabroye has since added Citronelle, Mocha, Tiramisu and half a dozen others with similar parentage to his lineup. These cultivars have somewhat fuzzy leaves in strong, solid colors and make sizable clumps more than a foot across. They bloom in late summer, although the flowers aren’t particularly showy.

Conclusion

Dubbed the “Heuchera King” by Allan Armitage for his prolific work with coral bells, Dan Heims of Terra Nova Nurseries, Oregon, also added H. villosa to his program in recent years. His resulting introductions include Georgia Peach, Crème Brûlée and Southern Comfort.