Rhododendron viscosum
A native eastern North American deciduous shrub up to about 2.5 m tall with dark leaves and highly fragrant white funnel-shaped flowers that open in early to midsummer in moist, acidic soil, attracting pollinators.
Common Names
Swamp Azalea, Swamp Honeysuckle, Clammy Azalea, White Swamp Honeysuckle, Cory Azalea, Hammock Sweet Azalea
Summary
Rhododendron viscosum, Swamp Azalea, is a deciduous shrub native to the eastern United States with an upright spreading multi-stem habit, typically 2 to 5 ft tall with a similar spread, it bears clusters of 3 to 12 very fragrant funnel-shaped flowers that are white to pale pink with long slender tubes, opening after leaf emergence in late spring to early summer, and the fragrance is strong and musky or clove-like, leaves are dark green, obovate to oblanceolate, and the shrub commonly grows in damp acidic soils in wetlands or swampy woodlands, for cultivation swamp azalea prefers moist acidic well-drained soils and can tolerate some wet conditions but not permanent flooding, it does best in sun to part shade with protection from harsh afternoon sun and benefits from mulch to retain moisture, it can be propagated by seed, semi-ripe cuttings, layering, or grafting, and pruning after flowering helps shape and promote next year's buds, it is often used in shrub borders near ponds, damp areas, and woodland gardens, and it attracts bees and hummingbirds, all parts are poisonous if ingested, hardiness is USDA zones 4 to 9
Lifecycle
Perennial
Height
3-5 feet
Spread
36-60 inches
Hardiness Zones
Zones 4-9
Sunlight Requirements
Ideal sunlight ranges from partial shade to full sun; it prefers sun-dappled shade or high open part shade and may scorch in full sun, with some afternoon shade in warm regions and full sun often optimal in cooler regions.
Soil Type
Acidic, moist, well-drained soil rich in organic matter, pH 4.5–5.5
Soil Drainage
Moist, well-drained, acidic soil.
Soil pH
4.5-6.0, Acidic soil
Bloom Color
White to pale pink
Bloom Time
Summer
Foliage Color
Dark green
Fall Foliage Color
Yellow, Orange, Purple
Leaf Lifecycle
Deciduous
Growth Rate
Approximately 0.5 feet per year, growth is slow to moderate, reaches about 5–8 ft tall in 10–20 years
Seasons of Interest
Spring, Summer, and Fall
Propagation Methods
Seeds, Cuttings, Layering
Attracts Wildlife
Attracts butterflies, hummingbirds
Taxonomy
- Taxonomic Rank
- Species
- Author
- (L.) Torr.
- Publication
- Fl. N. Middle United States 1: 424 (1824)
Superior Taxa
- Kingdom
- Plantae
- Subkingdom
- Pteridobiotina
- Phylum
- Angiosperms
- Order
- Ericales
- Family
- Ericaceae
- Subfamily
- Ericoideae
- Genus
- Rhododendron
- Subgenus
- Rhododendron subgen. Hymenanthes
- Section
- Rhododendron sect. Pentanthera
- Subsection
- Rhododendron subsect. Pentanthera
Synonyms
Rhododendron ornatum Rhododendron glaucum Rhododendron glaucum Rhododendron hispidum Rhododendron viscosum var. aemulans Anthodendron viscosum Azalea glauca Azalea nitida Azalea oblongifolia Azalea scabra Azalea serrulata Azalea virens Azalea viscida Azalea viscosa Azalea viscosa var. hispida Azalea viscosa var. montana Azalea viscosa var. nitida Azalea viscosa var. virens Rhododendron coryi Rhododendron oblongifolium Rhododendron serrulatum Rhododendron viscosum f. viscosum Rhododendron viscosum var. viscosum Rhododendron nitidum Rhododendron viscosum var. serrulatum Rhododendron viscosum var. montanum Azalea hispida Azalea tomentosa Azalea viscosa var. aemulans Rhododendron viscosum var. ornatum