St. Augustine grass (Stenotaphrum secundatum) is a popular warm-season turf species. It is the dominant turfgrass in the Southern United States, thriving particularly along the Gulf Coast, throughout Florida, and in Texas. This grass is characterized by its broad, coarse leaf blades and a distinctive blue-green color. It spreads aggressively via above-ground runners, known as stolons, which create a dense turf layer of sod.
Distinct Advantages of St. Augustine Grass
The primary appeal of St. Augustine grass is its superior tolerance to shade when compared to other common warm-season varieties like Bermuda or Zoysia grass. While it still requires approximately four to six hours of sunlight daily, it maintains a healthier appearance under tree canopy than many alternatives. This species spreads vigorously, which allows for rapid lateral growth and quick establishment from sod or plugs. This growth habit makes the grass highly effective at creating a dense turf layer.
This thick growth habit serves as a natural defense against the establishment of most common lawn weeds. By forming a solid mat of vegetation, St. Augustine turf effectively crowds out competing plants, reducing the need for chemical weed control. The resulting lawn is often described as lush and plush, providing a soft, consistent surface.
Specific Vulnerabilities and Risks
Despite its benefits, St. Augustine grass is highly susceptible to several significant pest and disease pressures. The Southern Chinch Bug (Blissus insularis) represents the most destructive insect threat, using its piercing-sucking mouthparts to inject a toxin while feeding on the grass blades. This feeding causes irregular patches of browning and dead turf, often mistaken for drought stress, which can expand quickly during hot, dry weather.
Fungal diseases pose a risk, particularly Brown Patch and Gray Leaf Spot, which are often exacerbated by high humidity and excessive moisture. Brown Patch, caused by Rhizoctonia solani, presents as circular or semi-circular areas of blighted grass with a distinct smoke-ring border. The St. Augustine Decline (SAD) virus is a serious problem, as it has no chemical control and causes a debilitating yellowing and decline of infected varieties.
St. Augustine grass lacks the necessary resilience to cold temperatures. It is highly susceptible to winter injury and frost damage, making it unsuitable for the cooler transition zones of the Southern U.S. This lack of cold tolerance restricts its cultivation to regions with consistently mild winters, as the grass struggles to recover from a deep freeze.
Essential Maintenance Needs
Maintaining a healthy St. Augustine lawn requires specific and consistent cultural practices to mitigate its vulnerabilities. Mowing height is critical, as the coarse blades must be cut high, ideally between 3 and 4 inches, to promote deep root growth and shade the soil. Mowing lower than the recommended height can severely stress the turf, increasing its susceptibility to insect and disease damage.
The grass has a high water requirement and must be irrigated deeply and infrequently to encourage the root system to grow downward. Applying about one inch of water per week, delivered across two or three watering sessions, ensures the soil is saturated to a depth of six inches. Watering should be completed in the early morning to allow the foliage to dry completely, preventing the onset of moisture-loving fungal diseases like Brown Patch.
St. Augustine is a heavy feeder and requires regular fertilization throughout the active growing season. Homeowners should plan to apply between three and six pounds of nitrogen per 1,000 square feet annually, with applications spaced six to eight weeks apart. This steady supply of nutrients is necessary to sustain the grass’s aggressive growth rate and maintain the dense, weed-suppressing turf layer.