Plant field guide
Azalea (Formosa)
Classic Southern Indica azalea with large lavender-purple flowers that blanket the plant in spring. One of the largest and most vigorous azaleas, creating a stunning mass of color. Semi-evergreen.
Growing requirements
- Scientific name
- Rhododendron indica 'Formosa'
- Sun
- partial shade
- Water
- moderate
- Height
- 60 in (152 cm) – 96 in (244 cm)
- Spread
- 48 in (122 cm) – 72 in (183 cm)
- Spacing
- Not recorded
- Hardiness zones & minimum temperature
- USDA 8–10; average annual extreme minimum from 10°F (-12.2°C). Hardiness does not predict local frost dates.
- Difficulty
- easy
Planting & seasonal timing
Northern Hemisphere planting months: not yet verified in our database.
Northern Hemisphere pruning months: April, May.
For the Southern Hemisphere, these seasonal windows shift approximately six months. Check your local frost forecast, soil temperature, and species requirements; calendar months are not a guarantee of planting safety.
Traditional Southern garden classic. Very vigorous - can grow 5-8 feet tall. Best in filtered shade. Not as cold hardy as other azaleas - zones 8-10. Spectacular in mass plantings.
Pruning
Prune immediately after bloom. Can handle heavy pruning for size control. Blooms on old wood.
Fertilizer
Azalea/Rhododendron fertilizer (acidic)
After flowering
Mulch
3 inches of pine bark or pine straw.