Mountain Laurel

Size, growth and what to expect

Mountain laurel is slow. Young plants under 15 years add about 5 inches of height and 3½ inches of crown width a year. Our growth estimator likewise files it in the slow class. Most mature plants stand 6 to 10 feet tall and 4 to 8 feet wide as a dense, rounded shrub, though on Appalachian slopes it occasionally becomes a small tree over 30 feet. The oldest stem dated by its rings was at least 65 years old.

The flowers open from late April into June, from buds formed the previous summer. Each cup is about an inch across, white to rose with purple-red markings inside, and bumblebees are its main pollinators. The capsules that follow are tiny, about 3/16 of an inch, yet each holds 300 to 700 seeds. Every part of the plant is poisonous to people and livestock.

It grows wild from southeast Maine to the Florida panhandle and west to Louisiana, in the mountains, the Piedmont and the coastal plain, often on rocky or sandy acid slopes.

How to grow Mountain Laurel

Mountain laurel takes part shade, deep shade or full sun, though the sunnier the spot the more steady moisture it needs. Give it average, sharply drained ground, and where the soil is heavy plant on a low mound. It fills a corner at full size, so set plants 5 feet apart and 4 feet off a path.

Plant while dormant. Saplings arrive potted with a dense, shallow root mass, so loosen the outer roots, dig wide and shallow, and keep the top of the ball slightly proud of grade. Backfill with native soil and mulch with leaf litter or pine straw, thinner near the stems. No stake is called for. Seed is dust-fine and needs light. Keep it damp in the refrigerator for eight weeks, then sow it on the surface of moist peat mix, uncovered, at room temperature under lights and a clear cover. Seedlings come up within a few weeks.

The roots sit near the surface, so water through the first two summers whenever the top inch dries, and never let the mulch disappear. Deer usually pass it by, but a hard winter changes their minds, so cage young plants. Snapping off spent flower clusters improves next year's bloom.

Mountain laurel sets some seed with its own pollen, but less than when bees bring pollen from another plant, so plant two or more if you want seed. Lace bugs stipple the leaves in hot full sun, and leaf spot follows still, damp shade, so a half-shaded, airy site dodges both. Every part of mountain laurel is poisonous, so keep prunings away from goats, sheep and other stock.