St. Augustine Soil pH Guide
Ideal pH range is 6.0-6.5. St. Augustine tolerates 6.0-7.5 but nutrient availability drops significantly above 7.0. High pH (above 7.0) locks out iron in the soil, causing iron chlorosis — yellowing blades with green veins. Quick fix for chlorosis: foliar iron sulfate spray at 2 oz per gallon per 1,000 sq ft. Long-term fix: pelletized sulfur at 5 lbs per 1,000 sq ft when air temps are below 75°F, recheck pH in 3 months. Low pH (below 5.5): apply pelletized lime per soil test recommendation. Always start with a soil test before adjusting pH.
Frequently Asked Questions
What pH does St. Augustine need?
Ideal range is 6.0-6.5, but St. Augustine tolerates a wider range up to 7.5. This makes it more flexible than centipede, which demands acidic soil.
Why is my St. Augustine turning yellow?
If soil pH is above 7.0, iron becomes unavailable even when present in the soil. This causes iron chlorosis — yellow blades with green veins. Apply chelated iron or lower pH with sulfur.
Where can Florida residents get a soil test?
UF/IFAS Extension offices offer free soil test kits for Florida residents. This is the best deal in lawn care. Private labs like Waypoint Analytical also work well.
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