St. Augustine grass is the most common turf species across Central Florida, providing a dense, blue-green lawn surface. Successfully maintaining this warm-season grass relies on the precise timing of nutrient delivery to support its active growth cycle. Applying fertilizer at the wrong time wastes product, feeds weeds, and risks damaging the turf or the local environment. Understanding the region’s subtropical climate and the grass’s biological needs is the foundation for an effective fertilization strategy.
Understanding the Central Florida Growing Season
St. Augustine grass is a warm-season turf that enters a semi-dormant state when temperatures cool during the winter months. During this period, the grass slows its growth and utilizes stored energy. Applying nitrogen-rich fertilizer during dormancy is counterproductive.
The grass begins to exit dormancy and “green up” in the spring as soil temperatures consistently rise.
Active growth, necessary for nutrient absorption, typically resumes once soil temperatures reach 50–55°F. In Central Florida, this active growth phase usually begins around March or early April. Waiting until the grass has visibly started growing prevents stimulating tender new growth that could be damaged by a late frost.
The Optimal Fertilization Schedule
The ideal annual plan for Central Florida St. Augustine grass involves three to four applications during the active growing season, from early spring through early fall. The first application should occur in early April, or about two weeks after the turf has visibly greened up. This initial feeding uses a balanced fertilizer to support the root system and spring growth.
The second and third applications should follow the first by eight to ten weeks, supporting summer growth. These mid-season feedings are important for maintaining the grass during peak stress, despite local restrictions. A final application is recommended in the early fall, typically September or early October, before the grass prepares for cooler weather. This late-season application should focus on potassium, which helps the grass store energy and increases tolerance to cold and disease.
Fertilizer Application Rules and Restrictions
Timing fertilizer application must align with local environmental rules, as many Central Florida counties have specific ordinances to protect water quality. The most significant constraint is the seasonal blackout period, which prohibits the use of nitrogen and phosphorus fertilizers during the heavy summer rainy season, typically June 1 through September 30. These restrictions prevent nutrient runoff into local waterways, where they contribute to harmful algal blooms.
Florida state regulations limit the amount of nitrogen applied at one time to a maximum of one pound per 1,000 square feet. Any fertilizer product used must contain slow-release nitrogen, with at least 30% to 65% being a controlled-release formulation. Applying fertilizer is prohibited when heavy rainfall (two inches or more in 24 hours) is predicted, or during any flood or storm warning. Applicators must also maintain a setback, avoiding application within 10 feet of any water body, though this reduces to three feet with a deflector shield.
Pre- and Post-Application Care
Proper preparation before and after fertilization maximizes nutrient uptake and prevents turf damage. Mow the lawn one to two days before applying fertilizer, ensuring nutrients reach the soil surface rather than settling on tall leaf blades. If the soil is dry, a light watering beforehand helps activate soil microbes and prevents the fertilizer from burning the turf.
Immediately after spreading the dry fertilizer granules, thorough watering is necessary to dissolve the nutrients and move them into the root zone. This initial irrigation activates the product, especially the slow-release components, and defends against fertilizer burn. After soaking, avoid mowing for a few days to allow the product to fully absorb into the soil and begin nourishing the St. Augustine grass.