K Is for Kalmia

Truth be told, I wanted to write an article about Kalmia or Mountain Laurel this spring, but an unexpected shortage left many garden centres devoid of this wonderful broadleaf evergreen. Now that I finally have them back in stock, I think it’s time to extoll the merits and unique beauty of this versatile shrub.

Kalmia latifolia
Kalmia latifolia

Kalmia latifolia is a native of the woodlands of Eastern North America (including southern Quebec) and was first introduced into early colonial gardens around 1624. While it is common to see wild bushes reaching heights of 15’ or more, cultivated dwarf varieties average 3-4’ tall and standard cultivars 5-6’ tall with light pruning. This species has been called many common names including Calico Bush (a reference to its intricate flower colour) and Spoonwood (carved into spoons by Indigenous peoples), but Mountain Laurel seems to have become the one we are most familiar with.


Despite its delicate appearance, Kalmia latifolia is quite cold hardy at USDA zone 5. Like other members of the Ericaceae family such as Rhododendron, Pieris, and Heather, it requires well-drained evenly moist organic soil with an acidic pH. If your soil is too wet, then Mountain Laurel will quickly develop root rot — so if this is the case with your garden then consider creating raised beds and protecting the root zone with bark mulch (without burying the stems) to maintain moisture during the heat of summer. The other planting tip is to avoid situating them anywhere near a sidewalk or drive where road salt may be used as they do not tolerate saline conditions.


Mountain Laurels are slow growing in their juvenile phase and despite being evergreen, are a bit brittle, so some distance from kid’s soccer balls and meandering large dogs would also be appropriate. They are one of the few flowering shrubs that can grow in any exposure, be it shade, full sun, or partial shade. That said, there will be fewer flowers in deep shade while those in full-sun exposures are often blanketed in blooms but are easily stressed out or scorched in dry spells, so the ideal would be open shade to partial sun. Air circulation is also an important factor as bushes cramped against buildings or overwhelmed by adjacent shrubs often develop unsightly leaf spots from fungus.


Flowering occurs from late spring into early summer (late May into June) with clusters of intricate flowers held in dazzling trusses. The buds are actually pleated (looking like fancy bonbons) and can be pure white, deep rose to red, shell pink, or even pale magenta in colour. With the exception of white-flowering cultivars, they open to five-sided cup-shaped blooms that are often two-toned (white with burgundy bands) or streaked like a kaleidoscope. Needless to say, they are some of the most impressive flowers we can grow in coastal gardens. An added bonus is that the stamens are arched so that when a pollinator explores the bloom it is batted and literally coated by pollen.

As previously mentioned, Mountain Laurels are slow growing, so any pruning should be minimal and be done immediately after the flowers have faded. It is also a good idea to deadhead the spent blooms (to divert energy into next year’s buds instead of seed), although it can de difficult to do by hand so have a pair of pruning scissors for this task. Fertilize with Rhododendron and Azalea food (as this also provides soil acidifiers) in April, but use it at half strength unless your plant is looking pale or chlorotic. Well, that’s about all you need to know about how to grow these beautiful shrubs, so I will leave with a shortlist of the most common cultivars.


‘Ostbo Red’

Kalmia ‘Ostbo Red’
Kalmia ‘Ostbo Red’

An older cultivar (1940), the first with red buds that open to soft pink flowers. 4-6’ tall and wide with pruning.

 

‘Elf’

Kalmia ‘Elf’
Kalmia ‘Elf’

A dwarf variety with pure white blooms, a good choice for an Alba Garden design. Grows 3’ tall and wide.

 

‘Sarah’

Kalmia ‘Sarah’
Kalmia ‘Sarah’

A semi-compact form with red buds that open to reveal coral-pink inner flowers. Grows 4-5’ tall.

 

‘Olympic Fire’

Kalmia ‘Olympic Fire’
Kalmia ‘Olympic Fire’

Reddish-pink buds that open to light pink flowers. Grows 6-8’ tall without pruning.

 

‘Peppermint’

Kalmia ‘Peppermint’
Kalmia ‘Peppermint’

Unusual pure white flowers with red stripes that radiate from the center. Grows 4-5’ high and wide.

 

‘Minuet’

Kalmia ‘Minuet’
Kalmia ‘Minuet’

As the names implies, this compact variety bears pale pink buds that open to spectacular blooms of white with a prominent maroon band. Grows 3’ tall.

 

‘Carousel’

Kalmia ‘Carousel’
Kalmia ‘Carousel’

The pale pink buds open to starburst white flowers that are heavily tattooed in cinnamon-purple. Grows 6-10’ tall without pruning.