Mountain laurel usually grows as a dense, rounded shrub, with branches that grow gnarlier as the shrub ages. It is a relatively slow-growing shrub, adding about one foot per year. While mountain laurel is particular about its soil needs, this plant is easy to grow in the right environment. It is a good flowering shrub for mass plantings in shady shrub borders, woodland gardens, or foundation plantings. It partners well with rhododendrons and azaleas. Mountain laurel is native to the eastern United States, from New England south to the Florida panhandle and west to southern Indiana down to Louisiana. All parts of the plant are highly toxic to humans and pets. Do not plant these shrubs too deeply. Make sure the shrub’s crown (the point where its trunk meets its roots) is not buried. Buried crowns will suffer from rot and your shrub will likely die. When they are young, water the shrubs well, and keep the soil moist and acidic by using a layer of wood chips or evergreen bark mulch. Feed the shrubs in spring with a plant food formulated for acid-loving shrubs, such as rhododendron food. Remove the flower clusters immediately after they have finished blooming. Pruning lightly after blooming will help keep the shrubs full and bushy.
Light
Mountain laurel is highly prized because it performs well in part shade, but deep shade may reduce its flowering and cause leaf spots. It can tolerate full sun but the deep-green leaves may turn yellowish.
Soil
These shrubs like cool, moist but well-drained, acidic soil (pH 5.0 to 5.5). Its natural habitat is woodsy areas near swampy zones, but not in soggy soil. It dislikes heavy clay soils. If you have dense soil, consider planting mountain laurel in raised berms or planters filled with a well-draining soil mix.
Water
A newly planted mountain laurel needs watering every three to four days for the first few weeks. Give it enough water to thoroughly moisten the soil without making it soggy. For the rest of the first growing season, water it about once a week. Ideally, the soil should always be moist, but once established this shrub has fairly good resistance to drought, as long as the soil does not dry out and overheat from too much sun exposure. In the absence of rain, water mountain laurel every two to three weeks in the spring and every week in the summer. Water it slowly and deeply until the first few inches of soil are moist to the touch.
Temperature and Humidity
The shrub will do fine in warm weather provided the soil remains shaded. It normally does not like the high temperatures and dense humidity of southern coastal climates, but some cultivars are somewhat more tolerant of these conditions.
Fertilizer
This shrub should be fed in spring with an acid fertilizer, such as one formulated for azaleas and rhododendrons. Feeding will encourage more vigorous blooming. For the amount, follow the instructions on the fertilizer label.
Types of Mountain Laurel
Mountain laurel cultivars offer various color options, including many that are bicolored. Most are four to six feet tall, but several dwarf cultivars that will reach just three feet in height. The European Kalmia Society provides a full list of cultivars; these are some of the most popular choices:
K. latifolia ‘Elf’: This cultivar has white flowers and grows to just three feet tall and wide.K. latifolia ‘Minuet’: This cultivar flowers with white centers speckled with cherry red markings and surrounded by cherry-red margins. It reaches a mature size of just three feet tall and wide.K. latifolia ‘Olympic Fire’: This shrub has red-pink buds that open to dark pink flowers; it grows 10 feet tall and wide.K. latifolia ‘Peppermint’: The flowers have red stripes that radiate from the flower center out to the edges of the petals, resembling hard peppermint candies. It grows 10 feet tall.K. latifolia ‘Firecracker’: This cultivar tops out at three feet in height and has intense red-colored buds that open white and then turn to light pink.K. latifolia ‘Sarah’: Blooms in late spring with red buds that open to become rich pink to coral color with dots on the petals. A slow-grower reaching four to five feet and ideal for hedges.
Pruning
Mountain laurel is a slow-growing shrub that requires little pruning. Dead or broken branches can be removed anytime. Shaping pruning should be done in the spring, just after blooming is completed. Spent flower clusters should be deadheaded after the blooms fade. Should your mountain laurel plants get too tall or gangly for your landscape design, cut them back almost to ground level to rejuvenate them. These tough shrubs can take a severe pruning when necessary. From stubs just a few inches above the ground, new foliage will arise, and your plants will mature into large shrubs once again in about ten years.
Propagating Mountain Laurel
Mountain laurel is fairly easy to propagate by rooting stem cuttings, though it will take up to six months. Growing mountain laurel from seed is possible but a finicky and lengthy process and not recommended. The seeds need to be collected at the right time before they develop their extremely hard seed coat, which can make the germination process take years. In addition, you will need to wait another ten years to see a seed-propagated mountain laurel reaching the stage where it blooms. Here’s how to propagate mountain laurel from cuttings:
Common Pests & Plant Diseases
Mountain laurel is susceptible to leaf spots and blights. It is also prone to borers, scale, whiteflies, and lace bugs. In heavy soils, mountain laurel can develop root rot, for which there is no cure. Affected plants will need to be removed.
