Fertilizing St. Augustine Grass in Florida: pH, Nutrient Ratios, and Mowing Practices for a Thick Green Lawn

Florida pro with St. Augustine clients having high calcium ratios. Asks best fertilizer this month for thick green lawn.

First: pH 6.5

St. Augustine turns chlorotic in alkaline soil.

Fertilizer Specs

• Quality turf fertilizer with micronutrients, especially iron.
• Sandy soil: 1 lb N/1000 sq ft every 30 days.
• Clay soil: half that rate.
• Low phosphorus, potassium ~½ nitrogen → 2-0-1 ratio (e.g., 24-0-12).

Mowing Is Critical

• Full sun, ≤2": mow every 5 days.
• 2.5": every 7–10 days.
• Shade, 3": every 10–14 days.

Don't Over-Fertilize

Excess N increases insect/disease susceptibility and thatch.

Follow-Up: Fertilizer Composition

No chlorine. Some sulfur/sulfates. Check what local golf courses use—golf course distributors know. Bermuda and St. Augustine need similar fertilizers.