How much nitrogen should a St.

Target: 2–4 lbs N / 1,000 ft² / year (UF/IFAS SL-21).

• Low maintenance / shade: 2 lbs.
• Standard sun lawn: 3–4 lbs.

Split schedule (Jacksonville = Zone 9a):

| Timing | Rate (lbs N/1k ft²) | Product Example | Notes | |--------|---------------------|-----------------|-------| | Mid-April (after full green-up, soil ≥ 65 °F) | 0.75–1.0 | 16-0-8 or 15-0-15 @ 5–6 lbs/1k | 50 % slow-release N (SRN). Pre-M if crabgrass history. | | Early June | 0.75–1.0 | Same blend | Skip if summer rains > 1″/wk + clippings returned. | | Mid-August | 0.5–0.75 | 15-0-15 or 0-0-7 + 0.5 lb N from SRN source | Last N before blackout. Potassium critical for winter hardiness. | | Optional “fall” (late Sept–early Oct) | 0.5 | 0-0-7 + 0.5 lb N only if soil test shows low K & no blackout | Duval/Clay/St. Johns counties: no N/P June 1–Sept 30 (local ordinances). |

Rules of thumb

• Max 1 lb soluble N / 1k ft² per application; max 0.7 lb water-soluble N if quick-release.
• Return clippings = –0.5–0.75 lb N/yr.
• Soil test every 2–3 yrs (P, K, pH). Target pH 5.5–6.5.
• Irrigate ¼″ after granular apps; avoid > ½″ rain forecast next 24 hrs.

Blackout compliance: Zero N/P June 1–Sept 30 in NE FL counties. Use 0-0-7 or 0-0-16 if K needed during blackout.

For a St. Augustine lawn in the Jacksonville, FL area (USDA Zone 9a–9b), the recommended annual nitrogen (N) application is 2 to 4 pounds of actual nitrogen per 1,000 sq ft per year, depending on soil conditions, grass health, and maintenance goals.

Practical Split Schedule (Recommended for Most Home Lawns):

• Spring (March–April): 0.5–1.0 lb N/1,000 sq ft (Use a slow-release fertilizer; green-up after winter dormancy)
• Early Summer (May–June): 0.5–1.0 lb N/1,000 sq ft (Supports peak growth; avoid high N in extreme heat)
• Late Summer (July–August): 0.0–0.5 lb N/1,000 sq ft (optional, only if lawn shows deficiency) (High heat + high N = stress/burn risk; skip if lawn is thick and green)
• Fall (September–October): 0.5–1.0 lb N/1,000 sq ft (Critical for root storage and winter hardiness; most important application)
• Winter (Nov–Feb): 0 lb N (Dormant period; fertilizing wastes product and risks runoff)

Total Annual N: 1.5–3.0 lb N/1,000 sq ft is sufficient for most lawns; 4 lb N/1,000 sq ft is only for high-traffic, irrigated, sandy soils with visible thinning.

Key Tips:

• Always use slow-release nitrogen (e.g., polymer-coated urea, sulfur-coated urea, or organic sources) to reduce leaching and burn risk — especially important in Jacksonville’s sandy soils and near waterways.
• Test soil every 2–3 years (UF/IFAS Extension offers low-cost kits); adjust for phosphorus/potassium needs.
• Never exceed 1 lb N/1,000 sq ft per application.
• Follow Florida’s Urban Turf Fertilizer Rule (Chapter 5E-1.003, F.A.C.): No nitrogen or phosphorus application from June 1–September 30 in many Jacksonville-area counties (Duval, St. Johns, Clay, etc.) to protect waterways. Check local ordinances — violations can result in fines.

Source: UF/IFAS Extension Publication ENH-10 (“St. Augustinegrass for Florida Lawns”) and Florida Department of Environmental Protection fertilizer regulations.

Note: If unsure about local restrictions or soil conditions, consult your county’s UF/IFAS Extension office (Duval: https://sfyl.ifas.ufl.edu/duval/). Licensed lawn care pros are recommended for commercial or complex sites.