Culture
Best grown in cool, moist, rich, acidic, humusy, well-drained soils in part shade. Mulch to retain moisture and keep root zones cool. Plants tolerate a wide range of light conditions (full sun to full shade), but are best in part shade (morning sun with early to mid-afternoon shade) in the St. Louis climate. Raised plantings should be considered in order to promote better drainage. Plants do not grow well in heavy clay soils. Remove spent flower clusters immediately after bloom. Prune lightly after bloom to promote bushy growth.
'Sarah' is noted for having better tolerance for sun.
Noteworthy Characteristics
Kalmia latifolia, commonly called mountain laurel, is a gnarled, multi-stemmed, broadleaf evergreen shrub or small tree that is native to Eastern North America (New England south to the southern Indiana, Louisiana and the Florida panhandle) where it is found in a variety of habitats including open rocky or sandy woods, cool meadows, balds, mountain slopes and woodland margins. It is noted for its excellent spring flowers and quality year round foliage. It typically grows as a dense rounded shrub to 5-15’ tall, opening up and developing gnarly branches with age. Notwithstanding its usual shrub habit, mountain laurel will rarely grow as a small tree (particularly on slopes in the Appalachian Mountains) to as much as 30’ tall. Flowers appear in terminal clusters (corymbs to 6” across), typically covering the shrub in late May-June for several weeks with an often exceptional bloom. Each flower (to 1” across) is cup shaped with five sides and ranges in color from rose to white with purple markings inside. If not deadheaded, flowers give way to non-showy brown fruits (3/16” dehiscent capsules) that persist into winter. Elliptic, alternate, leathery, glossy evergreen leaves (to 5” long) are dark green above and yellow green beneath and reminiscent to the leaves of rhododendrons. All parts of this plant are toxic if ingested. Kalmia latifolia is the state flower of Connecticut and Pennsylvania.
Mountain laurel has acquired a number of different common names over time including ivy bush, spoonwood, calico bush and American laurel. Linnaeus named the genus herein after Swedish botanist Peter Kalm (1716-1779) who explored plant life in parts of eastern North America from 1747 to 1751.
Genus name honors Pehr Kalm (1715-1779), Finnish pupil of Linnaeus, who was sent by the Swedish government in 1748 to report on the natural resources of North America.
Specific epithet means broad-leaved.
'Sarah' is a compact shrub that typically matures to 4-5' tall over the first 10 years. It features ornamentally attractive red flower buds. Flowers open pinkish-red to coral pink with markings. Flowers bloom in late May-June. Undulate, glossy deep green leaves of this cultivar are smaller and have more twisting than leaves of species plants. New leaves emerge with burgundy hues.
Problems
Susceptible to leaf spots and blights. Also susceptible to borers, scale, white fly and lace bugs.
Uses
Superior flowering shrub for groups or massing in shrub borders, cottage gardens, woodland areas or wild/naturalized areas. Hedge. Foundations. Compliments rhododendrons and azaleas.