Flame Azalea
Rhododendron calendulaceum
- Native to:
- United States
Judy Gallagher (www.flickr.com)
Taxonomy
- Division:
- Magnoliophyta | - Flowering plants
- Family:
- Ericaceae
- Genus:
- Rhododendron
- Species:
- Rhododendron calendulaceum
- USDA Symbol:
- RHCA4
Growth Characteristics
- Life Cycle:
- Perennial
- Growth Habit:
- Shrub
- Height:
- 450 cm
- Light Requirements:
- Part Shade
- Drought Tolerance:
- Low
- Bloom Months:
- may,jun
- Bloom Colors:
- yellow, orange, red
- Landscaping Shrub:
- Yes
Wildlife Benefits
- Butterflies & Moths:
- ★☆☆☆☆ Documented Lepidoptera association (GBIF)
- Caterpillars:
- ★☆☆☆☆ Recorded caterpillar host plant (HOSTS Database)
Keystone Species Ranking
- Caterpillar Keystone:
- ★★★★☆ Butterfly & moth species supported by this genus (NWF)
Host Plant for Caterpillars
Garden & Ecology Notes
- Wildlife Value:
- butterflies, hummingbirds
- Fragrant:
- Yes
- Fall Color:
- yellow, orange, red
Soil Requirements
- Soil Type:
- rich, well-drained loamy soil
- pH:
- 4.5 - 6.0 (acidic)
- Drainage:
- excellent drainage required
- Moisture:
- consistently moist
- Notes:
- Prefers cool, shaded environments
Propagation & Germination
- Stratification:
- Cold/moist stratification required — 60–90 days
- Germination Time:
- 14–42 days
- Notes:
- Seeds require light for germination and should be surface-sown. Maintain consistent moisture and temperatures around 70°F.
The above propagation data sourced from Claude AI
Pre-treatment: Mix 0.1 - 0.2 gram of seed with between 4 and 8 grams of talc and sift over the surface of moist media.
Establishment: Most mortality occurs during the slow-growth, 2-leaf period when seedlings can become necrotic and die. By mid-March with longer day lengths, seedlings start to grow. Excessive temperatures can cause damage to the growing terminals.
Source: npn.rngr.net
ORGHPS Germination Guide: Requires light or the seed is very fine. Surface sow and expose to light. * sprinkle seed on 10 cm damp sphagnum moss; cover with clear plastic pop bottle cut in half; transplant seedling to acidic mix in shade outdoors when 5 cm high; protect from rodents and give protection in cold frame first winter