Bermuda grass (Cynodon dactylon) and St. Augustine grass (Stenotaphrum secundatum) are two distinct warm-season turfgrasses commonly used across the southern United States. While both thrive in high temperatures and provide a dense green lawn, they differ significantly in their physical characteristics and the level of care they require. Understanding these differences is crucial for homeowners selecting the appropriate variety for their landscape and maintenance preferences.
Physical Identification and Texture
The most immediate way to tell these two grasses apart is by examining the width and texture of their leaf blades. St. Augustine grass has broad, flat, and coarse leaf blades (3 to 12 millimeters wide), giving the lawn a thick, almost tropical appearance. Bermuda grass features much finer, narrow blades (1 to 5 millimeters wide), creating a dense, softer, carpet-like texture often preferred for athletic fields and golf courses.
Differences also exist in how each grass spreads. St. Augustine grass propagates exclusively through thick, above-ground runners known as stolons, which are easily visible. Bermuda grass is more aggressive, spreading using both stolons and an extensive network of underground stems called rhizomes. The presence of rhizomes allows Bermuda grass to recover quickly and establish dense turf, but also makes it highly invasive and difficult to contain near flower beds or walkways.
Climate Tolerance and Shade Needs
Bermuda grass requires full, direct sun exposure to maintain its vigor and density, struggling significantly in even partial shade. This species is well-suited to heat and drought conditions, possessing high temperature tolerance and requiring less water than many other warm-season varieties.
St. Augustine grass is one of the most shade-tolerant warm-season grasses available, making it the preferred choice for lawns with mature trees or partial shade. While it tolerates shade, it is less resilient to prolonged drought or extreme cold compared to Bermuda grass. St. Augustine requires more consistent moisture to maintain its lush, dark-green color and shows signs of drought stress sooner than Bermuda.
Essential Maintenance Requirements
The practical effort required to maintain these two grasses differs substantially, primarily in mowing and fertilization schedules.
Mowing
St. Augustine grass needs to be mowed at a relatively high height, typically maintained between 2.5 and 4 inches, to promote deep rooting and prevent stress. Bermuda grass, especially hybrid varieties, performs best when cut very low, often between 0.5 and 1.5 inches. Achieving this low cut sometimes requires a specialized reel mower for a smooth, high-density surface.
Watering
Watering requirements reflect their natural drought tolerance. St. Augustine needs about 1 to 1.5 inches of water per week during the active growing season and requires deep, consistent irrigation to prevent thinning. Bermuda grass is more efficient with water usage and can maintain health with less frequent watering, though deep watering is still recommended to encourage deep root growth.
Fertilization and Pests
Both grasses are heavy feeders, requiring regular fertilization to support vigorous summer growth. St. Augustine grass generally requires a total application of 2 to 4 pounds of nitrogen per 1,000 square feet annually for optimal health. Bermuda grass also has high nitrogen demands to support its aggressive growth and maintain its intense color. St. Augustine is susceptible to specific insect pests, such as chinch bugs, while the density of a well-maintained Bermuda lawn often helps suppress many weed species.