1. Iron chlorosis (nutrient uptake blocked by high pH)
Likelihood: HighIron is present in most soils but becomes unavailable to azalea roots when pH climbs above about 6.0. The classic sign is yellowing of new leaves while veins remain darker green (interveinal chlorosis). Clay or alkaline soils, recent lime application, or alkaline irrigation water increase risk.
Identification
- remove_circle_outlineNew leaves are pale yellow but leaf veins stay relatively green - classic interveinal chlorosis.
- remove_circle_outlineSymptoms first appear on the youngest growth in spring and persist through new flushes.
- remove_circle_outlineSoil test shows pH consistently above 6.0 or a lab report lists low available iron.
- remove_circle_outlinePlant otherwise shows little leaf drop; growth may be stunted if untreated.
The Fix
- 1Test soil pH with a home kit or send a sample to a lab; target pH 4.5-6.0 for azaleas.
- 2If pH is high, lower it with soil sulfur (follow label rates) or use acidifying iron sulfate for faster short-term correction.
- 3Apply a chelated iron foliar spray or soil drench labeled for woody acid-loving shrubs for quick symptom relief, then correct pH for long-term fix.
- 4Switch to an acid-loving fertilizer after bloom and follow label rates to avoid overfeeding; repeated small doses are safer than one heavy application.
- 5Retest pH in 3-6 months after amendments before repeated treatments.
