Mountain laurel (Kalmia latifolia) plants are a beautiful, flowering addition to any landscape. These bushes are not difficult to grow if you follow a few simple rules and there are many cultivars that offer various colors and sizes.
It is important that you do not confuse the mountain laurel shrub with the bay laurel tree. This shrub is poisonous and should not be used in food like its more famous counterpart.
As broadleaf evergreens, mountain laurels are multi-stemmed shrubs. They bear glossy, deep-green leaves that are attractive in all seasons. On older bushes, the branches can become quite gnarled, which lends to the character. It is the spring or summer flower display that makes them a special part of their natural woodland habitat.
The flowers appear in clusters, offering landscape value not only with their color but also with their unusual shape (particularly the buds). Bloom time is around the end of May or the beginning of June in zone 5.
Mountain laurel is native to woodlands in the eastern part of North America. The plant can be grown in USDA plant hardiness zones 5 to 9.
They are classified as shrubs that grow in shade and will tolerate deep shade. However, you will get more flowers if you plant them where they will receive a bit of sun. Select a location in light shade or dappled shade for optimal flowering.
These plants typically reach 5 to 8 feet in height (with a similar width) in the wild. It is possible for them to become even larger. Cultivars generally stay shorter and there are dwarfs available.
The mountain laurel cultivars available offer various color options and many are bicolored. Most are 4 to 6 feet tall, but there are also several dwarfs that will reach just 3 feet in height or less.
The European Kalmia Society provides a full list of cultivars, though these are some of the most popular choices:
- Bay State: Pink flowers with coral or salmon colors mixed in
- Black Label: Flowers bear a white center and margin, with an almost black band sandwiched in between
- Bridesmaid: Bicolored flowers with dark-pink on the margins and a white center
- Elf: White flowers and grows to just 3 feet tall and wide
- Firecracker: Buds are a deep-red, opening to become light-pink flowers; a bit narrower in shape than many cultivars, maturing to 3 feet tall by 2 feet wide
- Fresca: Flowers sport a chocolate-purple band on white petals
- Galaxy: Burgundy and white colors on star-shaped flowers that are formed quite differently from those on wild mountain laurels
- Madeline: Remarkable not for its floral coloration—which is white, tipped with pink and speckled with burgundy—but for the fact that it is double-flowered
- Minuet: White center speckled with cherry-red markings and surrounded by a cherry-red margin; reaches a mature size of just 3 feet by 3 feet
- Peppermint: Red lines radiating from the flower center out to the edges of the petals, reminding people of hard peppermint candies
- Silver Dollar: Another type whose flower is remarkable not for its colors (white, with sparse pink markings), but for its relatively large size of 1 1/2 inches across
- Tightwad Too: Noteworthy because its pink buds never open, which is a nice feature for those who prefer the look of mountain laurel in bud, rather than in full bloom
- Tiddlywinks: Medium-pink flowers and a dwarf that grows to 3 feet wide and tall
As evergreens with pretty flowers, mountain laurels boast a number of potential uses in the landscape, including in foundation plantings. If you garden in eastern North America, you may wish to play up their indigenous status by using them in woodland gardens as well.
Many people try to propagate mountain laurels by transplanting them from the wild. However, you are far more likely to have success if you purchase a balled and burlaped plant from a nursery. Digging up wild plants usually causes sufficient root damage that will thwart your efforts to save money.
The soil should be moist but well-drained. This combination is not always easy to achieve. Adding peat moss, compost, and sand before planting is a step in the right direction.
The soil pH of the ground should be on the acidic side. When growing acid-loving plants like mountain laurel, rhododendron, and azalea, it can be helpful use a fertilizer such as Holly-Tone, if your soil is too alkaline. This will acidify the soil over time.
Mulching will help retain some of the moisture the plants need. The mulch will also keep the soil cool, which mountain laurels like. Pine needles and wood chips can both make excellent mulches. Whichever kind of mulch you use, apply a 2 to 6-inch layer.
When planting mountain laurels, do not plant too deeply. Make sure the shrub's "crown" (where its trunk meets its roots) is not buried. Buried crowns will suffer from rot and your shrub will likely die.
Mountain laurel plants rarely need to be pruned. Pinching off the seed heads after blooming seems to promote better flowering for the next season, though. If you choose to prune (to make the shrubs bushier, for example), do so just after the flowering season has ended.
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’ time.
Similar Plants, Other Types of Kalmia
Mountain laurel shrubs are a close relative of rhododendrons and azaleas. All three shrubs belong to the heath family. They are related to their namesake bay laurel trees (Laurus nobilis) in name alone, though they are often confused for one another.
The common name for Kalmia latifolia derives from the fact that, when Europeans encountered it in the New World, it reminded them superficially of Laurus nobilis. While the foliage of the bay laurel is used as a culinary herb, mountain laurel is a poisonous plant.
The mountain laurel has a close association with another Kalmia, the aptly named "lambkill" (Kalmia angustifolia) shrub. It is another reminder of why scientific names are so important when discussing plants: Confusion over plant names can have dire consequences.
Another example of how misleading common names can occur with the cherry laurel (Prunus laurocerasus), which isn't a laurel at all. But it's a popular landscape plant, especially in the form of the more compact cultivar, Otto Luyken. The species plant (zones 6 to 8, full sun to partial shade) matures to 10 to 18 feet tall and 20 to 25 feet wide.