When does swamp azalea bloom?

Rhododendron viscosum typically flowers in June and July, producing clusters of fragrant white blooms after most other azaleas have finished.

What pollinators visit clammy azalea flowers?

Bees, butterflies and hummingbirds are drawn to the sticky, tubular white flowers, which release a strong clove-like scent that is most noticeable in the evening.

What growing conditions does this shrub prefer?

Swamp azalea grows best in part shade with consistently moist to wet soil, and is often found along stream banks, in bogs, and at the edges of wet woodlands.

Does swamp azalea keep its leaves in winter?

No. Rhododendron viscosum is deciduous and drops its leaves in fall after they often turn shades of orange or red.

Is Clammy Azalea toxic to dogs?

Yes. Clammy Azalea is listed as toxic to dogs by the ASPCA Animal Poison Control Center (aspca.org). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.

Is Clammy Azalea toxic to cats?

Yes. Clammy Azalea is listed as toxic to cats by the ASPCA Animal Poison Control Center (aspca.org). If your cat has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.

Is Clammy Azalea toxic to livestock?

The USDA PLANTS Database does not flag Clammy Azalea as toxic to livestock.

Is Clammy Azalea HOA-friendly?

Clammy Azalea is generally an HOA-friendly choice in the right placement, with moderate maintenance.

Clammy Azalea

Name: Pollinator Patch
Author: Pollinator Patch

Rhododendron viscosum

Last reviewed: September 2026

Rhododendron viscosum, the swamp azalea, is a deciduous shrub that blooms in June and July with fragrant white flowers, thriving in wet woodlands, swamp edges and bog margins across the eastern United States.

Clammy Azalea (Rhododendron viscosum) — Photo: (c) Tom Norton, some rights reserved (CC BY)

Clammy Azalea is toxic to dogs and cats.

Listed as toxic by the ASPCA Animal Poison Control Center (opens in new tab) (last reviewed 2026-05-21). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435and your veterinarian's emergency line.

Pollinator Patch flags toxic plants so you can choose a pet-safe native alternative for your yard.

The USDA PLANTS Database (opens in new tab) does not flag Clammy Azalea as toxic to livestock.

Light

part shade

Water

high

Size

36"–120" H × 36"–96" W

Bloom

Jun, Jul

Native to

AL, AR, CT, DE and 19 more states

Pollinators

bees, butterflies, hummingbirds

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Browse plants for this ecoregion

Piedmont Northeastern Highlands Northeastern Coastal Zone Northern Allegheny Plateau Northern Forests Middle Atlantic Coastal Plain Northern Piedmont Southeastern Plains Blue Ridge Ridge and Valley Central Appalachians Southern Coastal Plain Atlantic Coastal Pine Barrens

Clammy azalea is a native deciduous shrub that produces clusters of fragrant white or pink tubular flowers in early summer. This moisture-loving plant thrives in partially shaded areas and can reach 3-10 feet tall and wide at maturity. It prefers consistently moist soil and provides excellent seasonal interest with its showy blooms.

Growing Clammy Azalea

Grow Clammy Azalea in part shade and high water. Mature plants reach 36 to 120 inches tall and spread 36 to 96 inches wide. Expect moderate maintenance to keep it looking intentional in a front yard.

In an HOA neighborhood

Clammy Azalea is an HOA-friendly choice. Maintenance level: moderate. Tidiness: 4 out of 5.

Works well in: front yard, foundation, mid zone.

Requires consistent moisture to maintain appearance
Can become leggy without proper pruning

Wildlife value

Host plant for Azalea sphinx moth.

The fragrant flowers attract bees, butterflies, and hummingbirds during the June-July bloom period. This native azalea serves as an important nectar source for pollinators during the summer months.

Common questions

When does swamp azalea bloom?: Rhododendron viscosum typically flowers in June and July, producing clusters of fragrant white blooms after most other azaleas have finished.
What pollinators visit clammy azalea flowers?: Bees, butterflies and hummingbirds are drawn to the sticky, tubular white flowers, which release a strong clove-like scent that is most noticeable in the evening.
What growing conditions does this shrub prefer?: Swamp azalea grows best in part shade with consistently moist to wet soil, and is often found along stream banks, in bogs, and at the edges of wet woodlands.
Does swamp azalea keep its leaves in winter?: No. Rhododendron viscosum is deciduous and drops its leaves in fall after they often turn shades of orange or red.
Is Clammy Azalea toxic to dogs?: Yes. Clammy Azalea is listed as toxic to dogs by the ASPCA Animal Poison Control Center (aspca.org). If your pet has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.
Is Clammy Azalea toxic to cats?: Yes. Clammy Azalea is listed as toxic to cats by the ASPCA Animal Poison Control Center (aspca.org). If your cat has been exposed, call the ASPCA Animal Poison Control Center at (888) 426-4435.
Is Clammy Azalea toxic to livestock?: The USDA PLANTS Database does not flag Clammy Azalea as toxic to livestock.
Is Clammy Azalea HOA-friendly?: Clammy Azalea is generally an HOA-friendly choice in the right placement, with moderate maintenance.

These answers were drafted with an AI model from this plant's data. Verify care details with a local expert.

Native range data from the World Checklist of Vascular Plants (Kew). Pollinator and host plant associations compiled from GBIF, iNaturalist, and published ecological literature.

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