Margaret Lauterbach

Heuchera is easy to grow and adds color to gardens

Heucheras come in a variety of colors.
Heucheras come in a variety of colors.

“New” doesn’t always mean improvement, but the new attention paid to the genus Heuchera, or coral bells, is an exciting improvement to foliar shapes and colors in the ornamental garden. I grow them in a shade bed, but some are better adapted to sun than others. If you look at old garden books about perennial foliage plants, you won’t find much at all about Heucheras, but breeders have been busy and now there are more than 80 varieties offered by commercial sources. My shade bed receives morning sunlight, so is not deep shade.

The foliage is lobed, with leaves bringing red, purple, orange, yellow, pale green, silver, white and combinations of those colors. Varieties with predominating silver or frosty white can lighten a dark area, and so can those with light shades of the other colors. All send forth tiny red blossoms on long wiry stems that stand far above the foliage, giving rise to the common name “coral bells.”

This is an American native, a member of the saxifrage family. It was named for Johann Heinrich von Heucher, a botany professor at Wittenberg University in Germany, by his friend Carolus Linnaeus, who named many other plants too. The Germanic pronunciation would be HOY-kera, but most in America now pronounce it HEW-kera.

My Heucheras would probably be more voluptuous if they had more water, since in the wild Heucheras seem to grow best in scree (very coarse sand or light gravel) in mountain conditions. The scree would provide excellent, sharp drainage, but in their wild native conditions, frequent natural moisture and high humidity provide needed water. As for soil, those areas in which they’re native tend to have more acidic soil than we have, although in my yard I’ve not seen soil-related problems and they’re in soil, not scree. My Heucheras may have been bred to tolerate more alkaline soil.

In a properly-prepared bed they’re a delight, even though their coral bell flowers are comparatively insignificant. Their brilliant, sometimes patterned, foliage merit their own space. They’re not heavy feeders, but if you grow them in a container (where they really do shine), use a slow-release fertilizer that will feed over a three- to four-month time. They require little maintenance except for deadheading, and then those wiry stalks should be snipped as low as possible on the plant to avoid the pincushion appearance.

Heucheras are rarely affected by disease, and if they’re planted in the wrong place, chlorotic leaves and a failure to thrive will let you know they need to be moved. They’re actually pretty tough plants that will recover if misused or misplaced. Most of the foliar problems that arise are usually due to sunburn, bacteria, mold, dehydration or chemical burns. One variety, H. sanguinea, is susceptible to mildew. Improving the air flow, changing the pH of the leaves with baking soda application or using a commercial fungicide corrects that problem. Some have cured mildew with a spray of 50 percent skim milk, 50 percent water. Rust may be an issue if environmental conditions favor it, or a Pseudomonal disease that resembles rust will require the removal of the afflicted leaves and treatment with a copper-based spray.

Insect problems are few except for the destructive larvae of the strawberry root weevil, known in some areas as the black vine weevil. Adults eat V-shaped notches in leaves that causes only cosmetic damage to over 150 species of plants. They feed at night and take refuge in the soil during daylight when they and their larvae are vulnerable to nematodes. Adults don’t often feed on Heuchera leaves, but their larvae love the roots. If you can easily pull the whole plant up, the roots have been eaten by those larvae. These weevils cannot fly, and they generally stay within 30 feet of where they hatched.

Plantsman and plant breeder Dan Heims has applied hot water (between 100 and 120 degrees F.) to a Heuchera, killing the larvae feeding on roots, but not harming the plant. He made this treatment in winter.

You can simply avoid root-eating larvae by planting Heucheras in containers. Anju Lucas, head of perennials at Edwards Greenhouse, has had Heucheras in containers for several years. This year she’s very enthusiastic about a cultivar called “Black Pearl.”

Since vine weevil larvae are so destructive, especially on certain plants and shrubs, for instance, it might be wise to avoid planting Heucheras near peonies or some other weevil favorites such as lilacs, rhododendrons or azaleas. Cutworms occasionally cause damage, but Heucheras are not attacked by slugs, spider mites, white flies and many other pests.

Send garden questions to melauter@earthlink.net or Gardening, The Statesman, P.O. Box 40, Boise, ID 83707.

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