Featured Plants - Heuchera

Origin of Garden Heuchera

The coralbells are a group of American plants that are found wild mostly on slopes and cliffs from Connecticut to western Canada and south into Mexico. In general they grow as tufts of foliage, from which spikes of small flowers rise in spring to summer. They vary from forms only a few inches high ( eg. H. nivalis of the Rocky Mountain alpine zone) to forms over three feet tall (H. maxima of California).

Few of the larger wild species are considered garden plants, since the flowers of almost all are green or whitish and inconspicuous. Some small western species are attractive enough to be grown in the rock garden. H. hallii, H. pulchella (left) , H. hirsutissima, H. grossularifolia, H. merriamii, and smaller forms of H. cylindrica are pretty plants well suited to rock garden conditions. (For more on rock gardening go to the North American Rock Garden Society site.) One southwestern species, H. sanguinea, has excellent pink flowers and was hybridized with other larger, hardier species to produce the garden coralbells (eg. Bressingham hybrids) that dominated the market until the 1990s. H. sanguinea and all of the pink and red flowered coralbells are avidly visited by hummingbirds and are good nectar sources.

In the eastern species there are forms with handsomely colored foliage that have been recognized as good garden perennials in the last 20 years. There are two basic types of foliage coloration. The first is a general bronze-purple tint, similar to that found in the new growth of many plants, but lasting through the year. This important trait in heuchera probably came from H. villosa f. purpurea (left), a bronze-leaved wild form from the Upper South. Bronze-purple forms have been selected in many other garden plants from 'Crimson King' maple to the sweet potato 'Blackie.' The purple pigment in young foliage protects rapidly growing cells from ultraviolet light damage; in purple-leaved forms the genetic means for breaking down the purple pigments as the foliage matures apparently does not work. A second foliage coloration is that of green leaves with white or silver patches between the veins. This coloration is due to air space between the layers of leaf tissue and is found in plants other than heuchera (eg. Asarum and Cyclamen). This structure may increase the amount of light taken in by pigment cells in the leaf. Several of the larger eastern heuchera such as H. americana, H. pubescens, and H. longiflora, often show this coloration in wild plants. The trait has come into the newer hybrid cultivars from H. americana and H. pubescens (below). Other traits that have been bred into some of the new hybrids of the last decade are miniature size (from the Rocky Mountain alpine species) and larger flowers (from H. cylindrica and H. pubescens).

An explosion in new heuchera forms in the 1990s was touched off by the appearance of hybrids between Heuchera 'Palace Purple,' a cultivar with evenly bronze leaves, and H. americana 'Dale's Selection,' a cultivar with silver-mottled green leaves, among seedlings at Montrose Nursery, run by Nancy Goodwin in North Carolina. The best of these hybrids combined purple leaf background with silvery markings for a strikingly beautiful effect. As soon as the hybrids, distributed under the name 'Montrose Ruby,' appeared on the market, they were used as the base for many new hybrid combinations. Dan Heims, in Oregon, used 'Montrose Ruby' and a ruffled form of H. micrantha, as well as other garden cultivars, to yield many new hybrid selections, which were propagated by tissue culture and rapidly brought onto the horticultural market. Charles Oliver, in Pennsylvania, combined 'Montrose Ruby' with H. pubescens and the Rocky Mountain alpine species as well as with some of the older garden hybrids; he has been slower to introduce new cultivars. More recently, a number of leaf color mutations have been selected and most present-day breeding work consists of recombining these forms and the older cultivars.

Cultivation of Heuchera

Heuchera want well-drained, neutral soil. Generally, they will do best in light shade during at least the hottest part of the day. In full sun the foliage may discolor or die back during very hot spells in the summer. Wild alpine heuchera and miniature forms like the Petites grow well in gritty scree soil in rock gardens and remain small and graceful, combining well with other alpines. The Petites do well in rich garden soil, too, and they will be quite different looking – taller and much lusher and suitable for front of the border use. Heuchera 'Petite Pearl Fairy' on the left is growing in a lean scree soil; that on the right is growing in rich soil suitable for heavy-feeding perennials and bedding plants.

Heuchera 'Petite Pearl Fairy' in rich soil

The most magnificent heuchera we have seen were growing in trial gardens in Michigan and the Netherlands in very sandy neutral soil and in Lancaster Co., PA, where the soil was a limy yellow clay. The soil at The Primrose Path is acid loam with shale and coal, and our plants do much better with added ground limestone and nitrogenous fertilizer, either from manure or 5-10-5 chemical.

Heuchera hybrids grown for flowers are best used in groups so that the effect is more substantial. The larger foliage types are effective in small groups or even as single plants, but can also be used well as large plantings interspersed with deciduous ferns or hostas. Heucheras will provide a year-round presence when the other plants are no longer visible. As midsize foliage plants heuchera are so new to garden designers that their potential has not yet been realized. One of the great strengths of heuchera is that they are evergreen and that the foliage remains very attractive through the winter. When hosta have retreated underground, heucheras are still handsome. A large proportion of North American gardeners live in climates where it is cold enough in winter that there is nothing much happening in the garden but snow cover comes and goes. These gardeners should think about using heucheras and other plants that are attractive during the winter in place of many of the summer-only perennials.

Heuchera have few pests and diseases. Plants that are too moist and shady may get some fungus problems during the summer. Moving them to a different site should solve this. The worst insect pest of the heuchera-tiarella group is the Black Vine Weevil, Otiorhynchus sulcatus. Larvae of this beetle bore in the roots and crowns of various plants, eventually causing the top of the plant to die. There is one generation of weevils per year, with the adults active in western Pennsylvania in June and the larvae causing most of their damage in the late summer and early fall. Inspecting wilted plants and killing the larvae is usually the only control needed in the garden. Introducing beneficial nematodes every couple of years is a good idea for control of weevils and other soil pests.

AN INTRODUCTION TO HEUCHERA