Rhododendron Species, Flame Azalea

Rhododendron calendulaceum

Family: Ericaceae (er-ek-AY-see-ee) (Info)
Genus: Rhododendron (roh-do-DEN-dron) (Info)
Species: calendulaceum (kal-en-dew-LAY-see-um) (Info)
Synonym:Azalea calendulacea
Synonym:Azalea lutea
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6-8 ft. (1.8-2.4 m)


6-8 ft. (1.8-2.4 m)


USDA Zone 5a: to -28.8 C (-20 F)

USDA Zone 5b: to -26.1 C (-15 F)

USDA Zone 6a: to -23.3 C (-10 F)

USDA Zone 6b: to -20.5 C (-5 F)

USDA Zone 7a: to -17.7 C (0 F)

USDA Zone 7b: to -14.9 C (5 F)

USDA Zone 8a: to -12.2 C (10 F)

USDA Zone 8b: to -9.4 C (15 F)

Sun Exposure:

Light Shade


All parts of plant are poisonous if ingested

Bloom Color:





Bright Yellow

Bloom Time:

Late Winter/Early Spring

Mid Spring

Late Spring/Early Summer



Other details:

Unknown - Tell us

Patent Information:


Seed Collecting:

Unknown - Tell us

Foliage Color:

Unknown - Tell us

Bloom Characteristics:

Unknown - Tell us

Water Requirements:

Average Water Needs; Water regularly; do not overwater

Where to Grow:

Unknown - Tell us


This plant has been said to grow in the following regions:

Sebastopol, California

Hampton, Florida

Keystone Heights, Florida

Cleveland, Georgia

Tiger, Georgia

Roslindale, Massachusetts

Saugus, Massachusetts

Hurley, Mississippi

Asheville, North Carolina

Hendersonville, North Carolina

Lake Toxaway, North Carolina

Morganton, North Carolina

Lewisburg, Pennsylvania

Prospect Park, Pennsylvania

Conway, South Carolina

Lafayette, Tennessee

Richlands, Virginia

North Sultan, Washington

Harpers Ferry, West Virginia

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Gardeners' Notes:


On Dec 29, 2014, coriaceous from ROSLINDALE, MA wrote:

The Arnold Arboretum (Boston, Z6a) has a hillside dotted with flame azalea, and in bloom they are nothing short of spectacular. They bloom with the leaves and not before, flowering lasts for about 2 weeks. The colors vary widely: lemon to deep yellow, apricot, salmon, fawn, pinkish/"flesh", as well as brilliant orange and scarlet.

Many people detect no fragrance (I'm one), and those who can smell it don't all find it agreeable.

Performs well in full sun or light shade here. Like all rhododendrons/azaleas, this requires acid soil and prefers consistent moisture. Does not prosper in high heat. Dirr gives Z7 as its southern limit in eastern N. America.

Many cultivars have been selected. This is a parent of the Ghent hybrids.


On May 7, 2012, Violet88 from Raleigh, NC wrote:

Our flame azalea gets some sun only in the winter; when the oaks leaf out it's in almost complete shade. It's a little leggy, but blooms beautifully, early spring, here in Raleigh NC. This year it started blooming in February!
I have never watered it, except for an occasional bucket of water in the hottest driest summers--it's on the side of the house away from the hose. So it's safe to say this is a pretty un-fussy plant! The flowers are orange, but the top two petals are strong yellow. It has a citrusy smell when the weather is cool, which becomes somewhat pungent (not in an entirely nice way) when it gets hot. A great plant! I am going to buy a couple more native azaleas to go with it.


On May 10, 2010, Clary from Lewisburg, PA (Zone 6b) wrote:

Brilliant orange flowers every May, most fragrant when fertilized with fish emulsion. A very unique shrub!

I had planted these along the foundation of my house. I have since removed them. Constant watering, acidifying, and fertilizing is bad for the foundation. Chemicals leaching from cement are bad for plants, especially those requiring acidic soil. I wish I had known this before I planted them, for the sake of my cement foundation.

They never thrived due to the poor location but they did flower well and we enjoyed the fragrance very much.


On Jun 29, 2004, xyris from Sebring, FL (Zone 9b) wrote:

A spectacular flowering shrub of the Southern Appalachians, from southern PA and OH s to northern GA and AL. Perhaps there is no better place to see this plant in the wild than along the Blue Ridge Parkway, where it is possible to see examples of its continuous flower color variation from pale yellow to deep orange-red in early June. My father cultivated a large collection of forms of this species in western North Carolina.


On Aug 20, 2003, haleygem from Saugus, MA wrote:

The plant has a gorgeous color when in bloom however to much shade will make for few blooms. Grows in the shape of a tall shrub that is easy to trim and shape. Can be used as an edger or border plant.