wetland shrub
Smooth Azalea
Rhododendron arborescens
1 of 2Native to the Southeast and the Northeast
Mountains of New York and Pennsylvania to Kentucky, south to Alabama and Louisiana
- Light Partial shade Sun tolerance
- Moisture Moist Moisture preference
- Zones 5–8 Cold to heat range
- Bloom May–Jul Flowering time
- Height up to 20 ft to 6.1 m
- Life cycle Perennial Annual to perennial
In the garden
A wetland shrub for partial shade and evenly moist soil. Its white and pink flowers peak in June. At up to 20 ft, it needs room in rain gardens, pond edges, and damp low spots. Hardy in USDA zones 5–8.
Growing conditions
Light
Full sun Partial shade Full shade
Moisture
Dry Moist Wet
Hardiness zones
Find your zone:
When it blooms
The Smooth Azalea's white and pink flowers bloom May to July, peaking in June. This early-summer display draws butterflies and flower flies.
Smooth Azalea blooms white & pinkFoliage
Pollinators & wildlife
- Butterflies Silver-spotted Skipper
- Flower flies Oblique Streaktail
Butterflies that use this plant
Documented host and nectar records. Each links to a planting guide for that butterfly.
- Silver-spotted skippernectar
Full plant details
Where it grows
- Habitat
- WetlandThe wild plant community it grows in.
- Native range
- The Southeast and the NortheastUnited States (12): AL, GA, KY, MD, MS, NC, NY, PA, SC, TN, VA, WV. Where it grows wild on its own, by state and province.
- Native distribution
- Mountains of New York and Pennsylvania to Kentucky, south to Alabama and LouisianaThe same native range, usually more exact than the state list, and often noting where it has spread beyond it.
Growing conditions
- Light
- Partial shadeHow much sun it takes, from full sun to full shade.
- Moisture
- MoistThe soil dampness it prefers, from dry to wet.
- Hardiness zones
- USDA 5–8The cold-to-heat climate range it survives.
- Soil
- Moist, well-drained soilsThe soils it grows in naturally.
- Soil pH
- 4.2–5.7The acidity to alkalinity it tolerates (7 is neutral).
- Soil quality
- LowHow rich a soil it needs. Many natives prefer lean soil and flop in rich beds.
- Water use
- MediumHow thirsty it is, a rough guide to how often to water.
- Salinity tolerance
- NoneHow well it copes with salty soil, near roads or the coast.
- Lime (CaCO₃) tolerance
- NoneHow well it copes with chalky, lime-rich soil.
Growth & form
- Height
- up to 20 ft (to 6.1 m)Typical mature height.
- Life cycle
- PerennialWhether it lives a single season (annual), two (biennial), or returns for years (perennial).
- Growth rate
- ModerateA relative ranking versus other plants of the same type (USDA), not an absolute rate.
- Shape
- Semi-ErectIts overall silhouette.
- Root depth
- 12+ in (30+ cm)How far the roots reach, a guide to drought resilience and transplanting.
Flowers, foliage & fruit
- Type
- ShrubWhat kind of plant it is.
- Bloom
- May–JulWhen it flowers.
- Flower color
- White, PinkThe bloom color, or colors.
- Toxicity
- Poisonous if eatenWhether any part is poisonous to people or pets.
Propagation & seed
- Cold stratification
- Required (cold, moist)Whether seed needs a cold, moist spell before it will germinate.
- Propagation
- Bare root, container, cuttings, seedHow to start new plants.
- Seed
- ~0.5 million seeds per poundNotes on the seed and how to sow it.
- Seed spread rate
- SlowHow readily it self-sows. Slow or none means well-behaved, not a spreader.
- Seedling vigor
- LowHow strongly young seedlings establish.
- Vegetative spread
- NoneWhether it creeps outward or stays put in a clump.