1242 Kalmia latifoliaCommon Names: mountain laurel, calico bush Family: Ericaceae (heath Family)
Mountain laurel is a dense, bushy shrub that is usually less than 10 ft (3 m) tall with an equal spread. Occasional specimens may reach tree size, up to 30 ft (9 m) in height. Mountain laurel has leathery evergreen leaves that are glossy dark green, elliptic to oval in shape, 2-5 in (5-12 cm) long, and arranged alternately on the stems. With mountain laurel it’s all about the inflorescence, which is extremely showy. Individual flowers are bowl shaped, a little less than an inch (2.5 cm) across and may be pale pink, fuchsia, almost crimson or white, usually with darker pink markings on the inside of the corolla. Several flowers are borne in rounded clusters (corymbs) 3-4 in (7-10 cm) across. The buds that precede the flowers are dark pink and nearly as showy as the flowers. Mature fruits are inconspicuous dry capsules that eventually split open to release extremely tiny seeds.
This beautiful American native is very popular among horticulturalists and gardeners and many cultivars have been named. Most of the selections and hybrids originated from Appalachian stock and many may not perform well in other regions. ‘Bullseye’ has flowers that are white with purple bands. ‘Freckles’ has pale pink flowers with purple spots. ‘Bay State’ has flowers of a coral color. ‘Elf’ is a white flowered dwarf with smaller leaves and a maximum size of just 3 ft (1 m) across and 3 ft (1 m) tall. Another dwarf, ‘Tiddlywinks’ is similar in size with medium pink flowers.
: Kalmia latifolia occurs in montane forests from New Brunswick south throughout the Appalachian Mountains at elevations up to at least 5000 ft (1500 m). Along the Blue Ridge Parkway and other scenic roads in the Appalachian Mountains, the iconic mountain laurel is beloved by all except those who leave the road and try to walk though the typically impenetrable thickets. Mountain laurel (despite its name) also occurs on the Piedmont and upper Coastal Plain of the Gulf Coast from extreme northern Florida to Louisiana, where it grows along streams and on cool, forested slopes.
Light: Mountain laurel grows naturally in the wild in shade to partial shade. In cultivation it does well in partial shade and can tolerate full sun if the soil is not too dry. Mountain laurel gets its bushiest and flowers its best in full sun. It especially needs sun in late winter and early spring, and therefore does best under tall deciduous trees. Moisture: Like many other members of the Ericaceae, mountain laurel likes an acidic soil that is rich in organics and relatively moist, but never soggy. Once established, it can tolerate extended dry periods. Hardiness: USDA Zones 4 - 9 . Mountain laurel has a large north-south distribution, and plants from up north are not likely to do well down south, and vice versa. Therefore, when obtaining plants for your garden, be sure they have originated in your region. Most of the pretty cultivars available in the trade are from northern stock and probably will not do well in the South. Propagation: Mountain laurel can be propagated from greenwood cuttings and semi-ripe cuttings, but this is difficult and results are often disappointing. Seeds do not require pretreatment and can be sown when ripe or after storage for up to at least four years. The seeds are so tiny that they should be broadcast in flats and left undisturbed until seedlings are large enough to move into pots. Mountain laurel selections are now being propagated commercially by tissue culture. Under ideal growing conditions, mountain laurel colonizes from underground rhizomes and forms dense thickets.
Mountain laurel, no doubt one of the most beautiful native shrubs in North America, is at its best in semi-shaded locations (with high shade from big, deciduous trees). It is especially well suited to share a naturalistic woodland setting with such shade lovers as native azaleas (Rhododendron sp.), wild blueberries (Vaccinium sp.), and Sweetshrub (Calycanthus floridus), for example. A group of mountain laurels makes an outstanding specimen planting for a partially shaded landscape. Mountain laurel, being evergreen, is used in mixed shrub borders.
For the best flowering year after year, the slow growing mountain laurel should be pruned immediately after flowering. If left unpruned it becomes leggy and straggly and may not bloom every year. That said, an unpruned mountain laurel eventually takes on a picturesque form with contorted limbs and attractive gnarly bark exfoliating to a cinnamon colored inner bark.
There are only seven species in the genus Kalmia. All are evergreen shrubs native to North America and the Caribbean. Kalmia hirsuta (sandhill laurel) is a tiny version of mountain laurel that occurs in pinelands in the SE US.
Steve Christman 6/11/15