Diagnosing and Treating Iron Deficiency in St. Augustine Grass

Symptom: Lime Green Patches

Classic iron chlorosis. Interveinal yellowing on young leaves. Not nitrogen (which yellows old leaves first).

Quick Fix

• Granular chelated iron (e.g., Ironite, Sequestrene) per label.
• Liquid chelated iron spray for faster response (may blacken leaves temporarily if overdosed).

Root Cause & Long-Term Fix

• High soil pH (>7.0) locks up iron. Test soil.
• Overwatering/wet soil reduces iron uptake.
• Excess phosphorus ties up iron.

Organic Program

• Sugar (1 lb/250 sq ft) spring/fall.
• Organic fertilizer with iron (e.g., Milorganite, 6-2-0 + Fe).
• Compost topdressing lowers pH slowly.
• Deep, infrequent watering.

Local Resource

Calloway's Nursery (TX): degreed staff, Howard Garrett's books, organic products.

Not Fungus or Bugs

Fungicides/insecticides won't fix nutrient deficiency. Treat the cause, not the symptom.