Mountain laurel Kalmia latifolia
Mountain laurel (Kalmia latifolia) is an evergreen perennial shrub in the Ericaceae family, native to Eastern North America (Appalachian woodlands). It grows 1.5–3 m (4.9–10 ft) tall and 1.5–3 m (4.9–10 ft) wide, wants part sun to part shade and moderate water, and is hardy to about -30 °C (-22 °F). Space plants about 1.8 m (5.9 ft) apart.
Plan Mountain laurel in your garden →
Free. Draw your beds, then watch it grow through the year in 2D and 3D.
Mountain laurel at a glance
| Type | Perennial shrub, evergreen |
|---|---|
| Family | Ericaceae |
| Mature height | 1.5–3 m (4.9–10 ft) |
| Mature spread | 1.5–3 m (4.9–10 ft) |
| Spacing | 1.8 m (5.9 ft) centre to centre |
| Sun | Part sun to part shade, at least 4 h of direct sun a day |
| Water | Moderate; drought tolerance low, waterlogging tolerance none |
| Soil pH | 4.5–5.5 |
| Cold hardiness | About -30 °C (-22 °F) once established (roughly USDA zone 4) |
| Heat stress | Likely above about 30 °C (86 °F) |
| Flowering | from about May for 2–4 weeks (northern hemisphere; later in cold climates, earlier in warm ones) |
| Wind tolerance | Low |
| Pollinator value | Moderate |
| Edible | Not grown as food |
| Native to | Eastern North America (Appalachian woodlands) |
| Common in gardens of | 🇺🇸 United States |
Is Mountain laurel toxic?
- People: severely toxic
- Cats: severely toxic
- Dogs: severely toxic
- Parts: leaves, flowers, nectar, honey
Grayanotoxins cause vomiting, low heart rate and collapse; even honey from the nectar is poisonous.
If a child or pet may have eaten part of a plant, call a poison centre or vet straight away.
Companion planting: what to grow with Mountain laurel
No well-documented helpful pairing. Group it with plants that like part sun to part shade and moderate water.
Keep apart or take care
- caution With the Ericaceae family: Mountain laurel and rhododendrons are hosts of Phytophthora ramorum (sudden oak death), which spreads from infected foliage between neighbouring plants. Evidence B
- caution With English lavender: Acid-loving plants need pH 4.5–5.5, lavender prefers neutral to alkaline soil; one bed cannot suit both. Evidence B
Shared pests and diseases
- Phytophthora ramorum: Sudden oak death pathogen; rhododendron, viburnum, camellia and pieris spread it to oaks and larch. Evidence B
See Mountain laurel in a botanical garden
It grows in these sample gardens, which you can walk through in 3D:
- Brooklyn Botanic Garden (3 plants)
- New York Botanical Garden (4 plants)
Questions about Mountain laurel
- How far apart should I plant Mountain laurel?
- About 1.8 m (5.9 ft) apart, centre to centre. A mature plant spreads 1.5–3 m (4.9–10 ft).
- Does Mountain laurel need full sun?
- Part sun to part shade: at least 4 hours of direct sun a day.
- How much water does Mountain laurel need?
- Moderate water. Drought tolerance is low and waterlogging tolerance none.
- How cold-hardy is Mountain laurel?
- It tolerates about -30 °C (-22 °F) once established, roughly USDA zone 4.
- When does Mountain laurel flower?
- From about May for 2–4 weeks (northern hemisphere; later in cold climates, earlier in warm ones).
- Is Mountain laurel poisonous to cats and dogs?
- For cats it is severely toxic; for dogs severely toxic; for people severely toxic. Grayanotoxins cause vomiting, low heart rate and collapse; even honey from the nectar is poisonous.
- What grows well with Mountain laurel?
- There is no well-documented companion pairing for Mountain laurel. Group it with plants that like the same sun (part sun to part shade) and water (moderate).
Sources and evidence
Evidence grade B (B: extension service or peer-reviewed).
- USDA PLANTS Database, USDA NRCS
- Missouri Botanical Garden Plant Finder, Missouri Botanical Garden
- ASPCA Toxic and Non-Toxic Plant List, ASPCA
- Poisonous plants of North Carolina / Plant Toolbox toxicity, NC State Extension
- APS compendia of plant diseases (host ranges, alternate hosts), American Phytopathological Society
Notes and assumptions
- Needs acidic, humus-rich, well-drained soil and shelter from drying winter wind.
- Typical garden-form values; cultivars and local conditions differ.
Reference values for planning, not horticultural, veterinary or medical advice. Varieties, soils and local climates differ: check with a local nursery or extension service.
Related plants
- Blueberry Vaccinium corymbosum
- Rhododendron Rhododendron
- American cranberry Vaccinium macrocarpon
- Lingonberry Vaccinium vitis-idaea
- Bilberry Vaccinium myrtillus
- Satsuki azalea Rhododendron indicum
- Japanese andromeda (pieris) Pieris japonica
- Heather (ling) Calluna vulgaris