wetland shrub

Swamp azalea

Rhododendron viscosum

Native to much of the USA

Maine to Ohio, south to Florida and Louisiana

Light Partial shade Sun tolerance
Moisture Wet Moisture preference
Zones 4–10 Cold to heat range
Bloom May–Jul Flowering time
Height up to 15 ft to 4.6 m
Life cycle Perennial Annual to perennial

In the garden

A wetland shrub for partial shade and wet soil. Its white and pink flowers peak in June. At up to 15 ft, it needs room in rain gardens, pond edges, and damp low spots. Hardy in USDA zones 4–10.

Growing conditions

Light

Full sun Partial shade Full shade

Moisture

Dry Moist Wet

Hardiness zones

Find your zone:

When it blooms

The Swamp azalea's white and pink flowers bloom May to July, peaking in June. This early-summer display draws bees and hummingbirds.

Swamp azalea blooms white & pinkFoliage

Pollinators & wildlife

Bees Common Eastern Bumble Bee also Azalea Mining Bee, Abrupt Digger Bee
Hummingbirds Ruby-throated Hummingbird
Moths Hummingbird Clearwing
Also visited by
- Butterflies: Silver-spotted Skipper

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: Much of the USAUnited States (22): AL, CT, DC, DE, FL, GA, LA, MA, MD, ME, MS, NC, NH, NJ, NY, OK, PA, RI, SC, TN, VA, VT. Where it grows wild on its own, by state and province.
Native distribution: Maine to Ohio, south to Florida 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: WetThe soil dampness it prefers, from dry to wet.
Hardiness zones: USDA 4–10 · Canadian 6–6The cold-to-heat climate range it survives.
Soil: Wet soilThe soils it grows in naturally.
Soil pH: 4.0–7.0The 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: HighHow 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: LowHow well it copes with chalky, lime-rich soil.

Growth & form

Height: up to 15 ft (to 4.6 m)Typical mature height.
Life cycle: PerennialWhether it lives a single season (annual), two (biennial), or returns for years (perennial).
Growth rate: SlowA relative ranking versus other plants of the same type (USDA), not an absolute rate.
Shape: ErectIts overall silhouette.
Root depth: 14+ in (36+ 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.
Fruit/Seeds: ripens Feb–NovThe seed or fruit it sets after flowering.
Toxicity: Poisonous if eatenWhether any part is poisonous to people or pets.

Propagation & seed

Cold stratification: Not requiredWhether seed needs a cold, moist spell before it will germinate.
Propagation: Bare root, container, seedHow to start new plants.
Seed spread rate: SlowHow readily it self-sows. Slow or none means well-behaved, not a spreader.
Seedling vigor: MediumHow strongly young seedlings establish.
Vegetative spread: NoneWhether it creeps outward or stays put in a clump.