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Rhododendron arborescens (Smooth azalea)
Cressler, Alan

Rhododendron arborescens

Rhododendron arborescens (Pursh) Torr.

Smooth Azalea, Sweet Azalea

Ericaceae (Heath Family)

Synonym(s): Azalea arborescens, Rhododendron arborescens var. richardsonii

USDA Symbol: rhar3

USDA Native Status: L48 (N)

Rhododendron arborescens is a large, loosely branched shrub, 8-12 ft. tall with an equal spread. Glossy, bright green, deciduous foliage lacks the hairs on the underside of the leaves that other native azaleas have. Foliage turns deep red to purple in fall. Fragrant, funnel-shaped, white or pink-tinged flowers with protruding, red stamens cluster in subtle groups of 3 to 6 after the leaves appear.

Relatively tall and fast-growing for a native azalea, Rhododendron arborescens is one of the hardiest native white azaleas and one of the last azaleas to bloom in the spring. It is drought-sensitive and requires moist, partially shaded sites.


From the Image Gallery

8 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Shrub
Leaf: Dark Green
Size Class: 12-36 ft.

Bloom Information

Bloom Color: White , Pink
Bloom Time: Jun , Jul


USA: AL , GA , KY , MD , MS , NC , NY , PA , SC , TN , VA , WV
Native Distribution: Mountains of NY & PA to KY, s. to AL & LA
Native Habitat: Swamp forests; mt. bogs & stream banks; piedmont

Growing Conditions

Water Use: Medium
Light Requirement: Part Shade
Soil Moisture: Moist
Soil pH: Acidic (pH<6.8)
CaCO3 Tolerance: None
Soil Description: Moist, well-drained soils.
Conditions Comments: Sweet azalea is tall and fast-growing for a native azalea. It is one of the hardiest native white azaleas, and one of the last azaleas to bloom in the spring. Drought sensitive, it requires moist, partially shaded sites.


Warning: Rhododendrons contain poisonous substances and should not be ingested by humans or animals. Honey made from flowers also may be toxic. POISONOUS PARTS: All parts. Highly Toxic, May be Fatal if eaten. Symptoms include salivation, watering of eyes and nose, abdominal pain, loss of energy, depression, nausea and vomiting, diarrhea, weakness, difficult breathing, progressive paralysis of arms and legs, coma. Toxic Principle: Andromedotoxin. (Poisonous Plants of N.C.)
Conspicuous Flowers: yes

Value to Beneficial Insects

Special Value to Bumble Bees

This information was provided by the Pollinator Program at The Xerces Society for Invertebrate Conservation.


Description: Combine seeds loosely with sphagnum moss and sprinkle lightly over a 2:1 perlite/peat mixture. Germinate under mist or a plastic tent. Optimum temperatures for germination are 45-50 degrees. Transplant seedlings to acid soil with a high content of orga
Seed Treatment: No pretreatment is necessary.
Commercially Avail: yes

National Wetland Indicator Status

This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Delaware Nature Society - Hockessin, DE
Mt. Cuba Center - Hockessin, DE

Additional resources

USDA: Find Rhododendron arborescens in USDA Plants
FNA: Find Rhododendron arborescens in the Flora of North America (if available)
Google: Search Google for Rhododendron arborescens


Record Modified: 2016-02-16
Research By: TWC Staff

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