Known as alumroot or coral bells, heucheras are native to the United States. The first garden varieties had green leaves and pink flowers on tall stalks above the foliage. Sandra Mason, writing for the University of Illinois Extension, calls these "grandma's coral bells." Heuchera 'Palace Purple,' was the first dark-leaved variety. Since the 1990s, many hybrids in purples, silvers, mottled greens, reds and oranges have been cultivated. Many hybrids have been created through tissue culture, a scientific technique that propagates plants in test tubes.
Heucheras with Dark Foliage
Heuchera 'Palace Purple' was introduced in 1980, according to Lili Singer writing for the "Los Angeles Times," and quickly became popular. Numerous purple hybrids were developed, some with silver veining and curled foliage. Heucheras.com, a website dedicated to the heuchera, lists the varieties 'Obsidian' and 'Plum Pudding' as two of the best dark-leaved heucheras. 'Obsidian' has almost black foliage and 'Plum Pudding' has silver veining. Flowers are white and not showy.
Heucheras with Light Foliage
Varieties of heucheras with light-colored leaves are becoming as numerous as the dark-leaved varieties. 'Lime Rickey' was one of the first, a vivid yellow-green but with a tendency for leaf disease. Since then, varieties such as Heuchera 'Electric Lime' and Heuchera villosa 'Pastiche' are improvements and excellent choices, according to Heucheras.com. Orange leaf tones are well-represented by Heuchera villosa 'Caramel,' a vigorous grower. Some Heucheras, such as 'Autumn Leaves,' are in shades of red.
There are heucheras available that possess traits of the old-fashioned coral bells. 'Bressingham Hybrids' heuchera can have red, pink, or almost white flowers over traditional green leaves. Heucheras.com lists the variety 'Red Spangles' as an excellent red-flowered heuchera with green leaves. The actual flowers are small, but there are many on each stem, making a great cut flower. The heucheras grown for their foliage have flowers that can also be cut. Just add a few leaves to the bouquet.
According to Jennifer Schultz Nelson, writing for the University of Illinois Extension, the ability of heuchera species to cross with each other is the reason there are so many unique varieties. Heucheras are also able to cross with Tiarellas, combining traits from both species to create heucherellas, also know as foamy bells. Flowers are typically shaped in spikes like tiarellas, but with some of the leaf shapes and colors of heucheras.
Heucheras like a well-drained soil amended with organic matter, and older varieties prefer more shade, according to Sandra Mason. The newer varieties bred from Heuchera villosa, a heuchera native to the southeast, can take full sun if enough water is given. Heuchera breeder Dan Heims of Terra Nova Nurseries cautions against feeding heucheras, as too much nitrogen can kill a plant. Heucheras grow in USDA Plant Hardiness Zones 4 to 9.
Benefits and Problems
Heucheras are semi-evergreen, which lends a year-round interest to the garden. In addition, some of the newer varieties, such as 'Autumn Leaves' change colors with the time of year.
The main problem with heucheras is their tendency to develop woody stems and to heave out of the ground during the winter. Ciscoe Morris writing for "The Seattle Times" recommends cutting plants down to 1/8 inch above the ground in March. Some varieties scorch in too much sun and a few have leaf disease.