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Clammy Azalea

Rhododendron viscosum (rho-doh-DEN-dron vis-KOH-sum)

Family: Ericaceae Native Shrub (3-15 ft)

The swamp azalea is a woody, broadleaf evergreen or deciduous shrub in the Ericaceae (blueberry) family and is native to the southern and eastern United states. The genus name derives from the Greek words rhodo , which means rose, and dendron , meaning tree. Its common name rightfully infers a tolerance for damp, moist environments but it requires enough drainage to avoid roots in constant standing water. The swamp azalea likes part shade and can tolerate some sun. Avoid afternoon sun which can scorch the leaves. This shrub has very fragrant, sticky, white flowers that bloom from May to July and attract hummingbirds, bees, and other pollinators. It can be planted in naturalized landscapes with careful attention paid to its growing requirements. It grows 2 feet to 8 feet tall and about as wide. It is a spreading shrub. Use it as a specimen in a native garden or an understory shrub in woodland planting. Insects, Diseases, and Other Plant Problems: While these shrubs remain very popular for landscape use, many cultivars are susceptible to Phytophthora root rot—this leads to leaf loss, reduced vigor, branch dieback, and wilting. Implement good cultural practices first, such as improving drainage with organic matter or berms and avoiding overwatering or overfertilization. However, if you have a site with a history of this disease, consider planting a root rot-resistant alternative species. For suitable alternatives, see this video created by Charlotte Glen as part of the Plants, Pests, and Pathogens series. VIDEO Created by Elizabeth Meyer for " Trees, Shrubs and Conifers " a plant identification course offered in partnership with Longwood Gardens. More information on Rhododendron .

Source: NC State Extension Gardener Plant Toolbox ↗ NC State Extension Gardener Plant Toolbox, 56 attributes.

How it fits the guild

Guild layer 3 - Shrub (3-15 ft) Optimal soil pH Acid (<6.0)
See companions & conflicts ↓

Companions & Conflicts

Curated pairwise relationships between this plant and others in the library — who feeds whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.

No curated interactions recorded for this species yet.

Also noted by NC State

Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.

Full plant profile

Growing Conditions
Plant type
Native Plant; Perennial; Poisonous; Shrub
Life cycle
Woody
USDA zones
4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b
Light
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
High Organic Matter
Soil pH
Acid (<6.0)
Soil drainage
Good Drainage | Moist | Occasionally Wet
Available space
3 feet-6 feet
NC region
Coastal; Mountains; Piedmont
Mature size
Height: 2 ft. 0 in. - 8 ft. 0 in. | Width: 3 ft. 0 in. - 8 ft. 0 in.
Maintenance
Low
Canopy layer
3 - Shrub (3-15 ft)
Form & Appearance
Habit / form
Open; Spreading
Foliage
Broadleaf Evergreen; Deciduous; Semi-evergreen
Leaf color
Green; Red/Burgundy
Leaf type
Simple
Leaf arrangement
Alternate
Leaf margin
Entire; Serrate
Hairs present
No
Leaf detail
Alternate, simple, lustrous green leaves; smooth- or toothed-margined
Flower color
White
Flower value
Fragrant; Showy
Flower form
Raceme
Flower shape
Tubular
Flower detail
Very fragrant, sticky white flowers bloom from May to July in a terminal cluster, tubular, 5-parted.
Bloom time
Summer
Fruit type
Capsule
Fruit detail
Elongated capsule. Displays from July to October.
Wildlife & Ecology
Native status
Native
Origin
Southeast and west to Texas
Wildlife value
Members of the genus Rhododendron support the following specialized bee: Andrena (Andrena) cornelli. Tolerates damage by rabbits.
Attracts
Bees; Butterflies; Moths; Pollinators; Small Mammals; Specialized Bees
Food & Medicine
Harvest time
Fall; Summer
Fruit type
Capsule
Landscape Use
Landscape location
Naturalized Area; Woodland
Landscape theme
Butterfly Garden; Native Garden; Pollinator Garden; Rain Garden
Design feature
Specimen
Garden tags
#deciduous #drought tolerant #specialized bees #evergreen #nectar plant #poisonous #pollinator plant #Piedmont Mountains FACW #Coastal OBL #food source herbage #mammals #food source pollen #food source nectar #hummingbird friendly #food source summer #food source fall #Audubon #problem for dogs #problem for horses #problem for cats #bee friendly #wet soils tolerant #larval host plant #heat tolerant #rabbit resistant #understory shrub #NC Native Pollinator Plant #naturalized area #NC native #native shrub #moth friendly #wildlife friendly #woodland #rain garden
Problems & Resistance
Insect problems
Azalea Lace Bug; Azalea Plant Bug; Azalea Caterpillar; Azalea Leafminer; Azalea Stem Borer; Azalea Bark Scale; Azalea Whitefly; Azalea Pest Management Calendar; Pests of Azalea
Disease problems
Southern Blight of Herbaceous Ornamentals
Problems
Poisonous to Humans; Problem for Cats; Problem for Dogs; Problem for Horses
Resistant to
Heat; Rabbits; Wet Soil
Poison severity
Low
Poison parts
Bark; Flowers; Fruits; Leaves; Roots; Seeds; Stems
Poison symptoms
While the plants are known to contain toxins, ingestion of moderate amounts of azalea (nectar or leaves) poses little toxic hazard.
Toxic principle
Grayanotoxins
Contact dermatitis
No
Toxicity summary
Low severity poison; parts: Bark; Flowers; Fruits; Leaves; Roots; Seeds; Stems

Planted at Hunnicutt

Nobody’s planted this one yet.