St. Augustine grass (Stenotaphrum secundatum) is a popular warm-season turfgrass known for its thick, dense, blue-green appearance, thriving in hot, humid climates. Its robust growth habit provides excellent ground cover, making it a favorite for residential and commercial landscapes. While this species is most commonly established using vegetative methods like sod or plugs, growing it from seed is possible with specific preparation and care.
Understanding the Limitations of St. Augustine Seed
The vast majority of St. Augustine grass found in lawns is propagated vegetatively using sod or plugs. This is because most commercially desirable varieties do not produce enough viable seed for large-scale collection and sale. The seeds that are produced often have extremely low germination rates, and the resulting seedlings are highly susceptible to common diseases like gray leaf spot.
The few seeds that do germinate can also lead to non-uniform turf, with variations in color, blade width, and growth rate across the lawn. Finding reliable, pure St. Augustine seed is challenging, and any available seed is generally very expensive. Homeowners should understand this process is difficult and involves higher risk than using sod or plugs.
Preparing the Soil for Seeding
Thorough soil preparation is essential for successful germination and establishment. Begin by completely removing any existing vegetation, including weeds and old turf, using a non-selective herbicide or mechanical removal to prevent competition. Conducting a soil test is advisable to determine the existing pH and nutrient levels; St. Augustine grass performs best in a slightly acidic to neutral pH range, ideally between 5.0 and 7.5.
If the soil is heavily compacted or composed of dense clay, till it to a depth of four to six inches to ensure good root penetration and drainage. Incorporating organic matter, such as compost or loamy topsoil, improves the soil structure and nutrient retention. Good drainage is paramount, as St. Augustine grass will not thrive in waterlogged conditions, which can lead to seedling disease. After amending and tilling, rake the ground smooth and level to create a clean, even seedbed.
Sowing and Initial Germination Steps
The optimal time for sowing St. Augustine seed is in the late spring or early summer, once the risk of frost has passed and soil temperatures are consistently warm. Warm-season grasses like St. Augustine require temperatures between 80 and 100 degrees Fahrenheit for best growth. If viable seed is obtained, the recommended seeding rate is approximately one-third to one-half of a pound per 1,000 square feet.
To ensure even distribution, divide the seed in half and apply each portion in opposing directions across the area using a broadcast spreader. Plant the seed very shallowly, either lightly raked into the top quarter-inch of soil or pressed onto the surface for proper light exposure. After sowing, lightly roll the area to establish firm seed-to-soil contact, which is essential for moisture absorption and successful sprouting.
The most critical factor during this stage is maintaining constant moisture in the top layer of the soil until germination occurs, which can take several weeks. Water the seeded area two to three times per day with a light mist or spray, avoiding heavy saturation that could wash the seeds away. Keep the seedbed consistently damp, but not soggy, for the initial two to three weeks until the seedlings visibly emerge.
Establishing and Maintaining the Seedlings
Once the seedlings have germinated, transition the watering schedule to promote deep root growth. Gradually reduce the frequency of watering while increasing the duration, allowing the water to soak deeper into the soil profile. This encourages the roots to grow downward, making the young turf more resilient to heat and dry conditions. The first deep watering should soak the soil to a depth of three to four inches.
The first mowing should occur when the grass blades reach three to four inches high, using a sharp blade set to its highest setting. Remove no more than one-third of the blade height at any single mowing event to prevent stressing the young grass. Delay fertilization until the seedlings are visibly established, typically six to eight weeks after germination. At that point, apply a light application of a starter fertilizer, which aids in root development.