Saint Augustine grass is a popular choice for homeowners seeking a dense, lush lawn in warmer climates, particularly across the southern and coastal United States. This perennial, warm-season turfgrass is valued for its ability to create a thick, carpet-like covering that effectively suppresses weeds. Its vigorous growth and attractive appearance make it a favored species for residential and commercial landscapes.
Identification and Ideal Growing Conditions
Saint Augustine grass (Stenotaphrum secundatum) is a warm-season species characterized by broad, flat leaf blades and a coarse texture. It presents a distinctive deep green to blue-green color, contributing to a plush, uniform appearance when properly maintained. It spreads aggressively by means of stolons (above-ground runners), which root at the nodes to quickly establish a dense sod.
The grass thrives naturally in subtropical and tropical environments, commonly found across the Gulf Coast and southeastern states (USDA zones 8 through 10). While it performs best in full sunlight (at least six to eight hours daily), it is also highly shade-tolerant compared to other warm-season turfgrasses. This tolerance allows it to grow effectively in areas with moderate shade.
For optimal health, Saint Augustine grass prefers well-drained, fertile soil, though it adapts to a range of soil types with a pH between 5.0 and 8.5. It exhibits tolerance for saline conditions, making it common in coastal areas. The grass grows most actively when temperatures are between 68°F and 86°F (20°C and 30°C) and requires high humidity.
Essential Care and Maintenance
Proper mowing directly impacts the turf’s health and density. The recommended cutting height ranges between 2.5 and 4 inches, with taller heights preferred for shaded areas or during environmental stress like extreme heat. Mowing at this height helps the grass blades shade the soil, which retains moisture and promotes deeper root growth.
Mowing frequency should ensure that no more than one-third of the leaf blade is removed during any single cut, preventing excessive stress. During the active growing season, this often requires mowing once a week. Using a sharp mower blade is important, as dull blades tear the grass, leaving ragged edges that increase susceptibility to disease.
Watering should follow a deep, infrequent schedule to encourage an extensive root system. The grass requires about one inch of water per week, and it is best to water in the early morning to minimize leaf wetness and reduce the risk of fungal disease. Signs of under-watering include the grass blades folding in half or the lawn retaining foot impressions.
The grass has a high nitrogen requirement, needing between 2 and 4 pounds of actual nitrogen per 1,000 square feet annually during the growing season. Fertilization typically begins after the lawn has fully greened up in the spring and continues through the summer. Applying iron sulfate or chelated iron between fertilizer applications can enhance the green color without stimulating excessive growth.
Establishing a new Saint Augustine lawn is most commonly achieved using sod or plugs, as viable seed is uncommon. Planting is most successful during the active growth period, typically from late spring through late summer. New sod requires frequent, light watering until the roots establish a connection with the underlying soil.
Addressing Common Threats
The southern chinch bug (Blissus insularis) is a destructive pest that feeds by sucking sap and injecting a toxic substance into the grass blades. Infestations are most severe in hot, sunny, and dry areas, often appearing near sidewalks or driveways. Damage first appears as irregular patches of yellowing grass that rapidly turn brown and die, often mistaken for drought stress since the areas do not recover after watering.
Adult chinch bugs are small (about 1/5 of an inch long), with black bodies and white wings marked by a distinctive black triangle. Homeowners can confirm an infestation using a flotation test: a bottomless can is pressed into the soil at the edge of a damaged area and filled with water, forcing the insects to float. Managing thatch (the layer of dead material between the soil and green growth) is an important cultural practice, as chinch bugs thrive in thick thatch.
Fungal diseases pose a significant threat, particularly in warm, humid conditions or when the turf is stressed. Brown Patch (Rhizoctonia solani) is common during periods of cool nights, warm days, and high soil moisture, often affecting the grass in circular patches. A sign of this disease is the ease with which the leaf blade can be pulled from the runner at the soil line.
Gray Leaf Spot (Pyricularia grisea) flourishes in warm, wet weather. This disease is identifiable by small, oval spots on the leaf blades that are tan or gray in the center with a dark purple or brown border. Over-fertilization with nitrogen can exacerbate Gray Leaf Spot, and avoiding late afternoon or evening watering helps prevent fungal diseases by reducing the duration of leaf wetness.
A healthy, dense Saint Augustine lawn naturally resists weed encroachment, but pre-emergent herbicides can be applied to control annual weeds like crabgrass. The grass is sensitive to certain herbicides, and applications must be made carefully, avoiding high temperatures, to prevent turf damage. Maintaining the recommended mowing height and proper density remains the most effective defense against weeds.