Mountain laurel: long admired in the wilderness, these beautiful flowering plants can add splendor to your garden as well

Flower & Garden Magazine, April-May, 1996 by Sharon Shreet

One Native Mountain Laurel (Kalmia latifolia) Is well-known throughout the Appalachians, growing so densely on mountain balds that locals call the impenetrable thickets "laurel hells." Mountain laurel's glossy evergreen foliage brightens the winter landscape; its trusses of lacy June blossoms veil slopes and ridges in blushing white.

Plentiful as they are in the wild, mountain laurels are uncommon in gardens, although they have been admired by gardeners since the early 1700s. These shrubs, hardly and easy to grow but difficult to propagate, had been difficult to obtain. Now, thanks to modern techniques and the talents of several plantsmen, mountain laurels are becoming widely available. Garden centers and mail-order nurseries offer cultivars that will attain the 10-foot size and stature of the wildings, as well as more compact and miniature types perfect for today's smaller gardens. The new cultivars also boast flower colors as various as pristine white, pale pink delicately edged in crimson, deep pink and white with broad bands of wine-purple.

Botanists discovered variants--including banded flowers and miniature plants--in native stands of mountain laurel over a century ago, but success eluded hopeful breeders for decades. Then C.O. Dexter, a highly regarded rhododendron breeder, collected and raised the richest pink wild mountain laurels to be found, selecting for ever-deeper colors among their progeny. The father-and-son team of Peter and Edmond Mezitt used those plants to make controlled crosses and develop intense pink flowers with red buds.

The greatest breakthrough came with the work of Dr. Richard Jaynes, who made hundreds of controlled crosses of mountain laurels during his 25 years at the Connecticut Agricultural Experiment Station and since his retirement in 1984. He determined the inheritance of flower and foliage characteristics, allowing him to introduce many of today's most popular cultivars. In 1981 Dr. Jaynes also recognised the potential of micropropagation, or tissue culture, for cloning mountain laurels and was the first to use it for these plants. With micro-propagation, gardeners can enjoy the blooms of the newest mountain laurels in as few as five years, instead of the 15 to 20 years it would have taken in the past.

Mountain laurels will bloom in sun or shade, with clusters of starry buds that open over a three-week period. The cup-shaped flowers usually vary in color from the buds, imparting the charm of an informal bouquet to the mixed trusses. Individual blossoms are sculpted with five lobes. Each lobe bears two pouches that encircle the flower center, often carrying spots of contrasting color. Ten stamens arch outward from the center, with each anther reaching a pouch that snugly envelops it. An alighting bee (or a gentle squeeze by curious fingers) pops the anther free and releases a shower of pollen. This intricacy of form is perhaps what prompted Peter Kalm, the Finnish botanist in whose honor the genus Kalmia is named, to describe the blossoms as resembling "the crater of the ancients."

With their graceful form, gnarled branches and broad leaves that remain uncurled during freezing weather, mountain laurels embellish both naturalistic and formal gardens. A single plant of a mountain laurel that flowers in a soft hue, such as 'Dexter Pink' or 'Pink Frost,' lends elegance to a mixed border and picks up the color show as earlier spring blooms are waning. Or try contrasting flower colors for a vibrant display. The white-flowering types, like "Silver Dollar' or the miniature 'Elf,' flatter cinnamon-banded 'Bullseye' or deep pink 'Sarah.' In a woodland, the shrubs often look best planted as they would grow in the wild, in drifts of similar colors. 'Ostbo Red' or 'Olympic Fire,' cultivars with red buds that open to pale pink blossoms, glamorize such a grouping, or use 'Snowdrift,' 'Candy' or 'Pink Charm' to mimic an Eastern forest.

When siting the plants, Southern gardeners should give them some shade; Northern gardeners should shelter them from harsh winter winds. Mountain laurel is native from Maine to Florida and rock-hardy to minus 20 degrees. It can be grown further north with protection and, if winter kills it back, can return vigorously from its roots. Like its relatives, azaleas and rhododendrons, mountain laurel needs an acid, well-aerated soil. Lighten heavy soils with pine bark and feed the plants once a year, before bud break, with an azalea-type fertilizer. The plants tolerate dry conditions but bloom best with adequate moisture, so water them during dry spells. Also note how sunlight affects the plants' performance. Full sun promotes more compact but slower growth in mountain laurels, and blossoms with red pigments develop deeper colors if they receive a few hours of direct sun each day.

Even under the best conditions, mountain laurels grow slowly but they are long-lived plants. Some have been found with more than 100 annual growth rings. The national champion mountain laurel is a white-flowering shrub growing beside a stream in the understory of an oak forest at the North Carolina Arboretum. It stands 25 feet tall with a 28-foot spread and an 18-inch-diameter trunk. Imagine the number of growth rings in that one!