How-to Guide
Growing Azaleas (Rhododendron spp.)
The short answer
Azaleas need acidic soil with a pH between about 4.6 and 6.0 and well-drained conditions. Because they are shallow-rooted, plant in a hole two to three times wider than the root ball but no deeper than the root ball, since planting too deep can be lethal; use raised beds if the native soil drains poorly.
Prune immediately after the spring bloom finishes, because heavy pruning after about June 30 reduces next year's flowers. A soil test is the best way to confirm the right acidity.
Soil and site
- Soil pH: acidic, about 4.6 to 6.0 (test the soil)
- Drainage: well-drained; build raised beds 8-12 inches high if soil is poorly drained
- Amend with an abundant supply of organic matter such as peat moss
- Shallow-rooted: never plant deeper than the root ball
Planting
- 1Dig wide, not deep — Make the hole 2-3 times wider than the root ball and no deeper than the root ball.
- 2Raise if wet — If native soil is poorly drained, hill soil 8 to 12 inches above grade or use timbers to form a raised bed.
Pruning basics and timing
Prune right after the spring flowering finishes. Heavy pruning after about June 30 can reduce next year's flowers, though light shaping later does no harm. After renewal pruning, pinch new shoots at 6 to 12 inches to encourage branching.
→ Azaleas (Rhododendron) are commonly listed as toxic to pets and people; check ASPCA or your Extension office before planting where children or animals are present.
Sources
Reviewed 2026-07-18. We cite university Extension, government, and established horticultural sources — and never invent pesticide rates or dangerous treatments.
- Clemson HGIC — Azalea Care — pH 4.6-6.0, plant hole 2-3x wider and no deeper than root ball, raised beds if poorly drained, prune after bloom, heavy pruning after June 30 reduces flowers.
- Oregon State University Extension — Spring care tips keep rhododendrons and azaleas thriving — Annual spring care and pruning timing for azaleas and rhododendrons.