Kalmia latifolia: Planting, Growing and Care

Botany

Kalmia is an evergreen shrub belonging to the Ericaceae family, like Heather and Rhododendron. Also known as Mountain laurel or American laurel, it originates from the forests, swamps and meadows of North America. The genus includes seven species, the most well-known being Kalmia latifolia which reaches 2 to 3 m in height in our gardens and has numerous cultivars with varied colours. Its relative, Kalmia angustifolia, more compact with a rounded habit, doesn’t exceed one metre in height and width. Less spectacular, Kalmia microphylla is a dwarf species (10 to 30 cm tall) that prefers damp and marshy areas.

Kalmia is a beautiful shrub with a bushy, dense, somewhat erect habit, more or less branched depending on the species, which can reach 2 to 3 m in height and spread (nearly 10 m in its natural habitat). Its trunk sometimes becomes twisted, especially with age. The very hard wood of its branches was once prized, particularly for making wooden spoons, hence its English nickname “Spoonwood”.

Slow to establish initially, Kalmia makes up for it with its longevity: some mother plants are around 60 years old! Its fine, shallow roots develop very slowly in the soil. As a result, it’s well suited to small gardens and urban gardens and can also be grown in containers on a terrace. It will take many years to form proper thickets (it grows about 1 m in ten years). Patience is rewarded by its truly unique flowering!

Kalmia latifolia: botanical illustration

Its spring flowering is enchanting! Between May and June, Kalmia becomes entirely covered with splendid flowers of very original design. This uniqueness has made the flower of Kalmia latifolia the emblem of the US states of Connecticut and Pennsylvania.

Emerging from dark pink or bright red pleated flower buds, the blooms resembling small sugar tulips open into flat, very flared or bell-shaped cups, 2 to 2.5 cm in diameter, formed of 5 petals that spread around a heart bordered by purple or golden-yellow stamens. They gather at the ends of branches in generous clusters that can bear up to a hundred flowers. Infinitely delicate, these slightly waxy corollas come in all shades of pink, ranging from white-pink, red, pale pink to purplish-pink in gradient with a darker reverse, evoking porcelain. Depending on the variety, these bell-shaped flowers take on a darker hue when mature or are veined with radiating bands like in Kalmia latifolia ‘You Can’. Some new cultivars like Kalmia latifolia ‘Tad’ even have surprisingly chocolate-coloured flowers.

An exquisite flowering that lasts a good month and is staggered: the beautifully ribbed flower buds resembling little meringues coexist with already opened flowers creating a pleasing contrast. Though unscented, they more than compensate for this lack of fragrance with their remarkable floriferousness.

Foliage, bud and flowers

After flowering, brown globular capsule-like fruits appear, persisting through winter.

Kalmia offers beautiful, graphic and elegant foliage all year round. It forms interesting bushy clumps for its evergreen foliage, somewhat similar to that of Rhododendron or Laurel. Its foliage consists of small glossy leaves 3 to 8 cm long, leathery and thick. Simple, alternate or opposite, lanceolate or elliptical depending on the variety, they form a permanent backdrop of intense glossy green. The branches of some varieties like Kalmia latifolia ‘Pinkobello’ take on reddish tones that contrast beautifully with the foliage.

Despite thick foliage and a robust clump, Kalmia fears three things: direct sun, cold winds and lime.

In nature, this heathland shrub thrives in partially shaded locations, on woodland edges where sunlight is filtered by trees. It appreciates sun exposure for a few hours in the morning or late afternoon.

While it tolerates a slight sea breeze, planting along a wall or in woodland, sheltered from cold, drying winds to preserve its evergreen foliage is essential. On the other hand, it isn’t afraid of cold. Kalmia is perfectly hardy and withstands temperatures down to -30°C, sometimes lower, provided it’s planted in a sheltered position.

Mountain laurel can be planted almost anywhere in France with a preference for cool, rainy oceanic climates: it likes coolness and high humidity.

While Kalmia is a low-maintenance shrub, it’s demanding regarding soil type. If the soil isn’t suitable, it will decline. Like its cousin the Rhododendron, Kalmia is a heathland shrub that absolutely needs acidic soil, rather cool, humus-rich but well-drained, and lime-free. Very sensitive to excess water, it fears stagnant moisture in heavy, asphyxiating soils.

The genus Kalmia is dedicated to Pehr Kalm, a famous 18th-century Swedish botanist who was one of the first to explore the flora in parts of North America.

Very versatile, Kalmia can be used in free hedges with other heathland shrubs, in beds with perennials, as a specimen plant and even in containers: plant taller varieties in a sheltered spot to create a free hedge or dress a wall, alongside Rhododendrons, Camellias, Azaleas, Pieris or Enkianthus. It will also be an ideal companion for Heathers, Hydrangeas, Japanese Maples and Magnolias. Its very slow growth and the modest size of some varieties allow it to be planted in containers: it will make a pretty decorative subject all year round with its evergreen glossy green foliage.

Species and varieties

The Most Popular

Our Favourites

Other Noteworthy Varieties

Kalmia latifolia Minuet - Mountain Laurel

One of the most floriferous varieties, with pale pinkish-white flowers and a compact size. Perfect for shaded beds or rockeries.

• Flowering time June, July
• Height at maturity 1 m

See the product sheet

Kalmia latifolia - Mountain Laurel

The standard species with pale pink flowers and a purple heart, highly hardy.

• Flowering time June, July
• Height at maturity 2 m

See the product sheet

Kalmia latifolia You Can - Mountain Laurel

This kalmia stands out with its pointed leaves and delicate pink blooms that deepen in colour as they mature. Exceptionally fresh and poetic!

• Flowering time June, July
• Height at maturity 2 m

See the product sheet

Kalmia latifolia Olympic Fire - Mountain Laurel

Vibrant pink buds open into white and pink flowers, brighter than the standard species. Features a particularly bushy habit.

• Flowering time June, July
• Height at maturity 1 m

See the product sheet

Kalmia latifolia Peppermint - Mountain Laurel

A large shrub with a rounded, densely branched form. Distinguished by its abundant pale pink blooms, adorned with radiating bands and red speckles. The candy-like flowers are utterly charming!

• Flowering time June, July
• Height at maturity 1,50 m

See the product sheet

Kalmia latifolia Tad - Mountain Laurel

This new variety is truly striking, with numerous chocolate-coloured flowers delicately edged and speckled with white.

• Flowering time June, July
• Height at maturity 1 m

See the product sheet

 

Kalmia latifolia Ewa - Mountain Laurel

Remarkably floriferous, covered in countless pale pink buds veined in deep red, which open into pale pink and white corollas.

• Flowering time June, July
• Height at maturity 1,30 m

See the product sheet

 

Kalmia latifolia You Can - Mountain Laurel

We love this unique kalmia for its pointed leaves and fresh, poetic pink blooms!

• Flowering time June, July
• Height at maturity 2 m

See the product sheet

 

Kalmia latifolia Minuet - Mountain Laurel

One of the smallest and most floriferous, with delicate pale pinkish-white flowers.

• Flowering time June, July
• Height at maturity 1 m

See the product sheet

 

Kalmia latifolia Olympic Fire - Mountain Laurel

Vibrant pink buds open into white and pink flowers, brighter than the standard species. Features a particularly bushy habit.

• Flowering time June, July
• Height at maturity 1 m

See the product sheet

Kalmia latifolia Elf - Mountain Laurel

A compact, dwarf variety with exquisite flowers and the smallest leaves in the genus. A perfect exclusive for small gardens!

• Flowering time June, July
• Height at maturity 75 cm

See the product sheet

• Kalmia angustifolia f. ‘rubra’ or Sheep Laurel: A smaller variety (0.80 cm) with deep red-purple flowers appearing slightly later in June-July.
• Kalmia latifolia ‘Ostbo Red’: Glossy green foliage sets off bright red buds that open into pale pink flowers. Very compact.
• Kalmia latifolia ‘Carousel’: White flowers streaked with intricate red patterns.
• Kalmia latifolia f. fuscata ‘Freckles’: A cinnamon-purple ring marks the interior of the white corolla.

Planting Kalmia

Where to plant?

Kalmia needs shade and acidity to thrive. It dislikes scorching sun and even more so… icy winds that damage its foliage. These are all factors to consider when planting it in your garden.

This shrub can be planted almost anywhere in France, except perhaps south of the Loire, as it dislikes intense sun in hot regions. It prefers soil that remains cool. It has a preference for cool, rainy climates, such as that of Brittany, where it grows very vigorously. In the wild, most heathland plants grow in woodland or woodland edges, where humidity is high. It can tolerate a few hours of sun in the morning or late afternoon.

It thrives in a shaded spot in the garden, sheltered from direct sunlight, along a wall or under the dappled shade of tall trees. Avoid overly dense shade, as it needs light to flower well. Ideally, it prefers west, southwest or northwest-facing exposures.

Very hardy, Kalmia is not afraid of cold, tolerating temperatures down to -20°C and coastal air, but dislikes storms and cold winds, which scorch its evergreen foliage: planting it in a sheltered spot away from cold draughts is essential.

Easy to grow, Kalmia is nevertheless particular about soil type: it needs acidity! It is an acid-loving plant that requires acidic soil, ideally close to heathland soil and free from lime.

Kalmia latifolia: a shrub that thrives in acidic soil

It also dislikes heavy, compact, waterlogged soils and grows best in cool, even moist, but well-drained conditions: Kalmia is very sensitive to excess water, so avoid waterlogged areas, especially in winter. Excess moisture encourages infection by Phytophthora, a soil-borne fungus that can kill the plant suddenly and completely.

If your soil is too chalky and/or too heavy, it’s best to improve it with heathland soil or… simply accept that Kalmia is not suited to your garden. Instead, opt for a less demanding shrub, otherwise you’ll need frequent applications of heathland soil and may end up with a weak plant prone to fungal attacks.

You can also grow it in a pot. Its compact size makes it ideal for container growing. It will thrive for many years in a large pot filled with two-thirds heathland soil and one-third good, lime-free garden soil, kept consistently moist.

Highly versatile in the garden, Kalmia works well in mixed borders with perennials, woodland edges, informal hedges, as a standalone specimen or in pots on a shaded terrace. Plant taller varieties in a sheltered, wooded spot to fill out a hedge, while low-growing varieties like Kalmia latifolia ‘Minuet’ suit cool rockeries or partially shaded borders. Very slow-growing, it’s a compact shrub, ideal for small gardens or urban spaces.

When to plant?

Kalmia can be planted year-round, avoiding frost and drought periods. Ideally, for best establishment, plant in autumn (September–November) in warm regions, or in spring (April–May) elsewhere.

How to plant?

Planting is the crucial step! The secret lies in soil quality.

• Avoid chalky soil: it won’t survive. If you still want to try: replace the excavated soil with a mix of heathland soil, leaf mould and peat. Chalky soils cause yellowing foliage (chlorosis), often leading to the plant’s death. Alternatively, line the planting hole with a plant-friendly membrane to prevent lime from leaching in.
• Avoid waterlogged areas: add gravel, pumice or clay pebbles to the base of the hole for drainage (its roots dislike stagnant moisture, especially in winter, and are prone to Phytophthora).
• Dig a hole 5–10 times wider than the root ball and 50 cm deep.
• Plant the shrub at soil level, in an ideal mix of 1/5 garden soil blended equally with peat, heathland soil, leaf mould and pumice.
• Apply an 8–10 cm organic mulch of pine bark or plant small perennials around the base to retain moisture and reduce watering: it likes its roots kept cool in summer.
• Water regularly with lime-free water (rainwater), but not excessively, for the first few weeks to keep the soil moist. In the first year, water generously during summer droughts.

Container gardening

The Kalmia is a shrub that is very well suited to container growing. We recommend opting for dwarf varieties such as Kalmia latifolia ‘Minuet’. It is essential to use a fresh, very well-draining mix, based on genuine ericaceous compost and well-rotted leaf mould, as it cannot tolerate waterlogged conditions. Choose a large container of around 30 litres (30 to 40 cm in diameter) and place a layer of gravel or clay pebbles at the bottom. When grown in pots, it will not tolerate even brief periods of drought. Kalmia requires water year-round, and if grown in a container, careful monitoring of watering will be essential. Apply a mulch or plant small perennials like dwarf cyclamen to help retain moisture.

Kalmia latifolia ‘Minuet’: an ideal variety for container growing

Maintenance, Pruning and Care

An established Kalmia requires little care to maintain its good health. Each spring, at the end of winter, you can lightly fork in some compost around the base to maintain soil fertility. You may also apply a fertiliser specially formulated for ericaceous plants.

Then spread a layer of organic mulch (pine bark or needles, leaf mould), renewed annually, to keep its roots cool during summer heat.

Kalmia needs water in summer but dislikes waterlogged conditions in winter. In summer: water 2-3 times per month, no more, using lime-free water. For this lime-intolerant plant, rainwater is preferable.

Being slow-growing, pruning is unnecessary. Only intervene to remove any dead branches or for very light shaping to maintain a balanced form. Remove faded flowers after blooming to prevent seed formation which exhausts the plant.

Possible diseases

When grown under good conditions, Kalmia shows little susceptibility to diseases and pests.

It is mainly vulnerable to fungal diseases caused by moulds. These issues usually stem from poorly drained soil or stagnant moisture around the roots. Its main enemy: Phytophthora, a soil-borne fungus whose attack can kill it as suddenly as it is devastating.

Phytophthora, literally meaning “plant destroyer” in Greek, thrives in persistently damp conditions, often due to overwatering. The foliage discolours, turns brown or red, then withers. The plant then dies rapidly. There is no treatment, but these problems are rare if proper growing advice is followed: plant in healthy soil, avoid waterlogged conditions, and improve drainage. If, despite these precautions, an attack occurs: remove affected plants and the surrounding soil. Never replant susceptible species in the same spot.

Intolerant to lime, Kalmia leaves discolour and turn yellow in case of excess lime (chlorosis). The culprit may simply be the watering water. Water only with rainwater.

Propagation

• By semi-ripe cuttings

After flowering, in July-August, take 10-20 cm long semi-woody or semi-ripe cuttings (i.e., from stems that grew in spring and begin their transformation from softwood to hardwood from July-August). Plant them in a light, well-draining growing medium. Regularly mist the cuttings with a sprayer. Pot them up as soon as they have formed roots. Overwinter them frost-free: a constant temperature of at least 20°C is essential for rooting within 8 to 10 weeks. Plant out in the ground the following spring if the root system is sufficiently developed.

• By softwood cuttings

Softwood cuttings are generally taken in spring, in May. Cut a stem below a leaf or bud. Remove the lower leaves. Plant in pots or trays in a growing medium composed of garden soil and river sand. Keep the cuttings regularly moist and maintain them under cover with a temperature of at least 20°C. Transplant them into individual pots, then into the ground when the root system is sufficiently developed. Several overwintering periods may be necessary.

• By layering

While layering is the least labor-intensive method to propagate Kalmia, you’ll need patience: root development is very slow. In August, bend one of its stems towards the ground, burying a portion to encourage rooting. Stake the aerial part. In autumn or the following spring, you can separate the layer from the parent plant once it has sufficient roots, by cutting the stem where it enters the ground.

Pairing Kalmia

Highly versatile, the Kalmia can be used in a mixed hedge with other ericaceous shrubs, in borders with perennials, as a standalone feature, or even in pots: plant taller varieties in a sheltered spot to create an informal hedge or adorn a wall, alongside Rhododendrons, Camellias, Azaleas, or Enkianthus. It also makes an ideal companion for Heathers, Hydrangeas, Hydrangeas, Japanese Maples, Magnolias, Pieris, Sarcococcas, Daphnes, or Skimmias.

Pair the pale pink Kalmia with Magnolia Fairy Blush® (Michelia hybrid) or Magnolia sieboldii

Its very slow growth and the modest size of some varieties make it suitable for planting in pots: it will be a lovely decorative feature all year round with its glossy evergreen foliage.

→ Discover more ideas for pairing with Kalmia in our advice sheet!