Flame Azalea
Flame azalea (Rhododendron calendulaceum) is a deciduous species native to the Appalachian Mountains. It bears non‑fragrant, funnel‑shaped flowers from late spring into early summer. Color ranges from yellow to deep orange and red, often before the plant has fully leafed out. Plants prefer open woodland light, cool roots, and acidic, well‑drained soils. Shrubs are upright and can reach small‑tree size in favored sites. This species is best adapted to cooler upland regions rather than the coastal plain.
At‑a‑glance
- Group/Class: species (deciduous)
- Height × spread: 4-8 ft × 8-10 ft (1.2-2.4 m × 2.4-3.0 m); occasionally taller
- Bloom window: late spring to early summer
- Color & flower form: funnel‑shaped flowers; yellow to orange to red; non‑fragrant
- Fragrance: 0 none
- USDA hardiness: USDA zones 5 to 7
- Breeder / Year / Origin: wild species; native to eastern USA
- Pet safety: avoid
How it differs
- Native, deciduous species with later bloom than many evergreen azaleas.
- Non‑fragrant flowers contrasted with scented native relatives.
- Taller, upright habit compared with compact evergreen groups.
- Naturally suited to cool, upland woodland conditions.
Strengths
- Cold hardy into Zone 5 where soils are acidic and drained.
- Attracts pollinators including butterflies and hummingbirds.
- Striking warm colors and good fall foliage.
- Adapted to naturalized woodland plantings.
Care in one minute
- Site in sun to light shade in cooler regions; provide afternoon shade where summers are hot.
- Soil: acidic and well drained; amend clay with organic matter; plant slightly high and mulch.
- Keep evenly moist during establishment; avoid standing water.
- Fertilize sparingly after bloom if growth is weak.
- Prune lightly right after flowering as needed.
Watch‑outs
- Poor performance on heavy or alkaline soils; chlorosis is common at high pH.
- Not recommended for the Coastal Plain in the Deep South.
- Slow to establish; protect from drought during the first years.
Best uses (tags)
woodland edge, naturalized, pollinators, cold‑tolerant, native
Provenance note
A southeastern U.S. native, R. calendulaceum is a key parent of many deciduous hybrid azaleas and is valued for late spring to early summer bloom in upland woodlands.
References
- NC State Extension – Flame azalea species profile
- Lady Bird Johnson Wildflower Center – Flame azalea
- Clemson HGIC – Azalea Planting (regional notes)
- ASPCA – Azalea (Rhododendron spp.) toxicity
Written by: Your Flowers Guide editorial team
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