St. Augustine grass is a popular choice for Texas lawns due to its dense, carpet-like growth and tolerance for heat. Maintaining a healthy St. Augustine lawn in Texas’s varied climate requires attention to a consistent fertilization schedule. The timing of nutrient applications is crucial to maximize the grass’s growth and health during its active growing season. Because of Texas’s immense size, a single statewide calendar for fertilization is ineffective, requiring precise, region-specific advice.
Regional Timing Differences Across Texas
Texas is not a homogenous climate zone, meaning a single calendar date for fertilization will not work statewide. The primary factor determining the appropriate time to begin spring fertilization is the soil temperature, which varies dramatically across the state. Warm-season grasses like St. Augustine only begin to absorb nutrients and actively grow once the soil warms up sufficiently.
The state is broadly divided into three climate zones: North Texas, Central Texas, and South/Coastal Texas. North Texas experiences colder winters and requires the latest start to fertilization. Coastal and South Texas benefit from an earlier onset of warm temperatures and an extended growing season.
The timing difference can be substantial, requiring Coastal Texas to start its schedule four to six weeks earlier than North Texas. Applications must be adjusted based on specific local soil temperature to be effective. Relying on the calendar alone risks wasting nutrients or damaging the turf.
The Spring Awakening: First Application Timing
The first spring application marks the end of winter dormancy and is the most important timing decision. The goal is to apply nutrients just as the grass breaks dormancy to fuel vigorous new growth. This moment is triggered by the soil temperature consistently reaching 65 to 70 degrees Fahrenheit, not the air temperature.
Visually, the grass will show signs of “green-up” by losing its straw-colored winter appearance and exhibiting patches of bright green blades. In Texas, this typically occurs between mid-March in the warmest southern regions and mid-April or early May in the northern parts of the state. Waiting for the soil to reach this temperature ensures the grass roots are active enough to absorb the applied nitrogen efficiently.
Applying fertilizer too early, while the grass is dormant or the soil is too cold, wastes nutrients that leach away. Early nitrogen applications can also promote tender top growth vulnerable to damage from a late-season frost. A slow-release nitrogen fertilizer is recommended for this first feeding to provide steady energy without forcing excessive growth.
Mid-Season Maintenance: Summer Fertilization Schedule
The summer months, representing the peak growing season, require a sustained fertilization schedule to support St. Augustine grass through the intense Texas heat. St. Augustine is a heavy feeder and needs regular nutrient replenishment to maintain color and density. Mid-season applications are typically spaced every six to eight weeks to align with the release rate of slow-release fertilizers.
For much of Texas, this means applications occur throughout June, July, and August. This frequency is necessary because high temperatures and active growth rapidly deplete soil nitrogen reserves. Maintaining sufficient nutrients helps the grass develop the deep root system needed to tolerate drought and heat stress.
Avoid applying fertilizer during periods of extreme heat, as this can stress the grass and increase the risk of burn. If the lawn is under severe heat or drought stress, delay the application until temperatures moderate. These summer feedings maintain color and prevent thinning under high-stress conditions.
Late Season Preparation: Final Application Timing
The final fertilizer application focuses on preparing St. Augustine grass for winter dormancy by strengthening the root system. This application should be timed when the grass begins to slow its top growth as temperatures cool, typically in September or early October. The goal is to provide nutrients for root development and energy storage without stimulating new leaf growth.
Do not fertilize too late in the fall with a high-nitrogen product, as this encourages soft, tender growth vulnerable to frost damage. The last application must be completed at least four to six weeks before the historical average date of the first expected frost.
This final application often involves a “winterizer” fertilizer, characterized by a higher ratio of potassium and a lower amount of nitrogen. Potassium aids in water regulation and disease resistance, supporting root strength and energy reserves for a quicker, healthier green-up the following spring.