St. Augustine grass (Stenotaphrum secundatum) is a popular warm-season turfgrass grown extensively across the Southern United States, particularly in the coastal and Gulf Coast regions. It is favored by homeowners for its dense growth habit, which effectively crowds out many weeds, and its distinct, appealing dark green to blue-green color. This grass spreads aggressively by above-ground runners called stolons, quickly forming a thick, lush lawn. It has better shade tolerance than many other common warm-season grasses like Bermuda grass, making it a choice for landscapes with mature trees.
Primary Cultivars of St. Augustine Grass
Floratam is one of the most widely recognized and planted St. Augustine cultivars, originally released in 1972 as a joint effort by the University of Florida and Texas A&M University. It is characterized by a coarse texture with wide, long blades and a vigorous, aggressive growth habit. Its stolons often display a noticeable purplish-red color, which can be a key identifier. This cultivar is particularly well-suited for full-sun environments and is the standard for many lawns in Florida and Texas.
Palmetto St. Augustine, developed in the mid-1990s, offers a finer blade texture and a semi-dwarf growth habit compared to Floratam, resulting in a softer feel underfoot. It is known for its attractive emerald-green color and is marketed as a versatile turfgrass. Because of its semi-dwarf nature, it requires less frequent mowing than taller varieties. Palmetto has become one of the most widely sold patented turfgrasses worldwide.
Seville is an example of a true dwarf cultivar, which presents the finest texture, creating a plush, carpet-like appearance. It has a distinctive blue-green color and a very low growth profile, meaning it can be maintained at a shorter mowing height than other types. Its compact nature means Seville produces less thatch than more vigorous varieties, simplifying long-term maintenance. This variety is often selected by homeowners who prefer a highly manicured, uniform lawn finish.
Raleigh St. Augustine was released in 1980 by North Carolina State University and features a medium-coarse blade texture and a deep blue-green color. It is a vigorous grower that can form a dense turf, making it a good choice for use in the transition zone of the Southeast. It has less shade tolerance and a coarser feel than popular patented cultivars. Its primary distinguishing feature is a specific adaptation to cooler temperatures.
Selection Criteria: Matching Grass to Environment
The best St. Augustine variety is determined by the specific environmental conditions of the lawn, with shade tolerance being the first consideration. Dwarf cultivars like Seville and Palmetto are highly valued for their ability to thrive in partial shade, requiring as little as four hours of direct sunlight per day. In contrast, the vigorous Floratam cultivar needs a minimum of six to eight hours of full sun to maintain its density and color; planting it in a heavily shaded area will cause it to thin out.
Cold Hardiness
Cold hardiness is a major factor for lawns in the northern range of St. Augustine’s territory. Raleigh St. Augustine was specifically bred for improved cold tolerance and is the most reliable cultivar for surviving winter freezes. Floratam and Seville, while excellent in heat, are significantly less cold-tolerant, and their use is often limited to the warmest regions of the deep South and coastal areas.
Drought Resistance
Drought resistance also varies among cultivars. Floratam is widely recognized for its robust drought tolerance once established, which is attributed to its deep and extensive root system. Palmetto also exhibits good performance under drought stress, though some research suggests Floratam may be superior in this trait. Newer varieties like Cobalt are being developed with superior water-use efficiency, demonstrating up to 30 to 50 percent less water usage than traditional cultivars in trials.
Pest Resistance
Pest resistance, particularly to the Southern chinch bug, is a significant concern for St. Augustine lawns. Floratam was initially released with resistance to this pest. However, new chinch bug biotypes have evolved, largely overcoming Floratam’s resistance, meaning most common cultivars, including Palmetto and Raleigh, are now susceptible. Homeowners must monitor for these pests, as no widely available commercial cultivar offers guaranteed long-term chinch bug resistance.
Essential Maintenance for a Healthy St. Augustine Lawn
Mowing
The recommended mowing height for most varieties is between 2.5 and 4 inches, with taller grass blades promoting deeper root growth and better shade tolerance. Never remove more than one-third of the leaf blade during a single session to prevent stress and scalping. This often requires mowing weekly, or even more frequently during the peak growing season in summer.
Watering
Watering should follow a deep and infrequent schedule to encourage a deep root system that improves drought tolerance. Instead of light daily sprinkling, the lawn should receive approximately one inch of water per week, either from rainfall or irrigation. The best time to water is in the early morning, which allows the grass blades to dry quickly, minimizing the risk of fungal diseases like gray leaf spot. Watering should only occur when the grass shows the first signs of wilt, such as a grayish color or folded blades.
Fertilization
Fertilization is necessary to support the vigorous growth and deep color of St. Augustine grass. The grass requires two to four pounds of actual nitrogen per 1,000 square feet annually, split into two or three applications during the growing season. A slow-release, complete fertilizer with a ratio such as 3-1-2 or 4-1-2 is recommended for spring and mid-summer feedings. St. Augustine grass is prone to iron chlorosis (yellowing blades), which can be corrected by applying a foliar iron supplement without stimulating excessive top growth.