Mountain Laurel

Kalmia latifolia (Ericaceae) is a broadleaf evergreen shrub native to eastern North America from Quebec and New Brunswick to Florida, west to Ohio and Tennessee. It typically grows 6 to 15 feet tall with a 9-foot spread, developing a dense, rounded form when young that becomes gnarled and open with age. The leathery, elliptic-lanceolate leaves are dark green above and yellowish beneath. Terminal flower clusters appear in May, each five-sided, cup-shaped bloom measuring about 2.5 cm across in white, pink, or red depending on cultivar. The stamens feature a unique catapult mechanism that flings pollen when triggered by visiting insects.

Mountain laurel requires acidic, well-drained, cool soil (pH 4.5 to 5.5) with mulch to retain moisture and moderate root temperatures. Part shade produces the best results, though the plant tolerates a range of light levels. It is slow growing and long lived. Blooms form on old wood, so pruning (including deadheading spent flower clusters) should occur immediately after flowering. All parts of the plant are highly toxic, containing grayanotoxins; it is poisonous to livestock. Documented pest and disease problems are minimal, with physiological shothole and carnation tortrix the only recorded issues. Hardy in Zones 4b to 8b.