Mountain Laurel
Kalmia latifolia · Calico Bush · Clamoun · Ivybush · Lambkill · Mountain-laurel · Sheep Laurel · SpoonwoodUSDA | Grow Zone
5-9Outdoors all year in zones 5 to 9. Anywhere colder, keep it as a houseplant.
- Light
- Partial to full shade
- Water
- Consistently moist soil
- Humidity
- 40-60%
- Temperature
- 60-75°F
- Difficulty
- Intermediate
- Growth
- Moderate
- Mature size
- 4-10 ft tall
- Pets
- Toxic to pets and humans
Kalmia latifolia, commonly known as Mountain Laurel, is a stunning evergreen shrub native to eastern North America. Renowned for its beautiful flowers and glossy leaves, it thrives in shaded areas and is a favorite among gardeners looking to add unique beauty to their landscapes.
Ask Vesper about Mountain Laurel
Ideal temperature
60-75°F is where it grows fastest.
Spacing and harvest
- Mature size
- 4-10 ft tall
- Plant apart
- 36-72 in
- Frost
- Hardy: survives frost
Everything it needs
9 essentials at a glance
Watering
Kalmia latifolia prefers consistently moist soil, especially during the growing season.
Water deeply once a week, allowing the top inch of soil to dry out between waterings. In hot summer months, increase frequency to twice a week if the soil dries out quickly. Signs of over-watering include yellowing leaves and root rot, while under-watering may cause wilting and leaf drop.
Light
Mountain Laurel thrives in partial shade to full shade, ideally receiving 4-6 hours of filtered sunlight daily.
Direct sunlight can scorch the leaves, so placing it under taller trees or near structures that provide dappled light is beneficial. It can tolerate some morning sun but should be protected from harsh afternoon rays.
Soil
This plant prefers acidic, well-draining soil with a pH range of 4.5 to 6.0.
A mix of peat moss, pine bark, and sand is recommended for potting. Ensure good drainage to prevent root rot, as Kalmia latifolia does not tolerate waterlogged conditions.
Humidity
Mountain Laurel enjoys moderate to high humidity levels, ideally between 40-60%.
To increase humidity, mist the leaves regularly or place a humidity tray filled with water and pebbles beneath the pot. Signs of low humidity include browning leaf tips and leaf drop.
Temperature
The ideal temperature range for Kalmia latifolia is 60-75°F (15-24°C).
It is hardy in USDA zones 5-9, tolerating cold down to -10°F (-23°C). However, it may struggle in extreme heat, so providing some shade during peak summer is advisable.
Fertilizing
Use an acidic fertilizer with an NPK ratio of 10-10-10 or similar, applying it every 4-6 weeks during the growing season.
Reduce feeding in fall and winter when the plant is dormant. Signs of nutrient deficiency include yellowing leaves and stunted growth.
Pruning
Prune Mountain Laurel after flowering to maintain its shape and remove any dead or damaged branches.
Use sharp, clean pruning shears to make clean cuts. Deadheading spent flowers can encourage more blooms, but avoid heavy pruning as it may reduce flowering the following year.
Repotting
Repot Kalmia latifolia every 2-3 years or when it becomes root-bound.
Choose a pot that is 1-2 inches larger in diameter than the current one. Signs it needs repotting include roots growing out of the drainage holes and stunted growth. When repotting, gently loosen the roots and place the plant in fresh acidic potting mix.
Propagation
Propagation can be achieved through semi-hardwood cuttings taken in late summer or by seed.
For cuttings, select healthy stems, cut them to about 4-6 inches, and remove the lower leaves. Dip the cut end in rooting hormone and plant in a moist, acidic potting mix. Keep the cuttings in a humid environment until roots develop, usually within 4-6 weeks. Seeds should be sown in a cold frame in late winter or early spring.
When it's unhappy
Leaf Spot
Why it happens
Fungal infections due to high humidity and poor air circulation.
How to fix it
Improve air circulation around the plant and apply a fungicide if necessary.
Root Rot
Why it happens
Over-watering or poorly draining soil.
How to fix it
Ensure proper drainage and reduce watering frequency. If root rot is severe, consider repotting with fresh soil.
Pest Infestation
Why it happens
Aphids, spider mites, or scale insects can attack the plant.
How to fix it
Inspect regularly and treat infestations with insecticidal soap or neem oil.
Wilting Leaves
Why it happens
Under-watering or extreme heat.
How to fix it
Check soil moisture and water thoroughly if dry. Provide shade during peak heat.
Yellowing Leaves
Why it happens
Nutrient deficiency or poor drainage.
How to fix it
Fertilize appropriately and ensure the soil drains well to prevent waterlogging.
Care through the year
Spring
In spring, focus on fertilizing as new growth begins. Monitor for pests and prune any dead or damaged branches after flowering.
Summer
During summer, ensure consistent moisture and provide shade during the hottest part of the day. Watch for signs of heat stress.
Fall
In fall, reduce watering as the plant enters dormancy. Prepare for winter by mulching around the base to protect roots from freezing.
Winter
In winter, keep the plant in a cool, sheltered location. Water sparingly, allowing the soil to dry out between waterings.
Toxicity & Safety
Kalmia latifolia is toxic to pets and humans if ingested. All parts of the plant contain grayanotoxins, which can cause symptoms such as nausea, vomiting, and cardiac issues. Keep it out of reach of children and pets.
Good to know
Why are my Mountain Laurel leaves turning yellow?
Yellowing leaves can indicate nutrient deficiency or over-watering. Ensure you are using an appropriate fertilizer and check that the soil drains well.
How often should I water my Kalmia latifolia?
Water your Mountain Laurel once a week, allowing the top inch of soil to dry out. In hot weather, you may need to water more frequently.
What type of soil is best for Mountain Laurel?
Kalmia latifolia thrives in acidic, well-draining soil with a pH of 4.5 to 6.0. A mix of peat moss, pine bark, and sand is ideal.
Can I grow Mountain Laurel in full sun?
While Kalmia latifolia can tolerate some morning sun, it prefers partial shade to avoid leaf scorch from direct sunlight.
When is the best time to prune Mountain Laurel?
Prune your Mountain Laurel after it has finished flowering to maintain its shape and encourage new growth.
Is Mountain Laurel toxic to pets?
Yes, all parts of Kalmia latifolia are toxic to pets and humans, causing symptoms like nausea and vomiting if ingested.
How can I increase humidity for my Mountain Laurel?
To increase humidity, mist the leaves regularly or place a humidity tray filled with water and pebbles beneath the pot.
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