A warm season grass, St. Augustine grows in the Gulf coast states as a primary turf grass, second in popularity to Bermuda grass. St. Augustine is a broad leafed, coarse textured grass that is dormant in winter and tolerates the heat and humidity of the deep South in summer. Frequently grown varieties of St. Augustine include Common, Floratam, Palmetto, Raleigh and Seville. These varieties differ in their susceptibility to common diseases such as St. Augustine decline, brown patch and take-all root rot.
An advantage of St. Augustine over Bermuda for landscapers is its tolerance for partial shade. Because it grows from stolons (above ground shoots), it is also easier to clear away from landscape beds and garden areas than grasses with rhizomes (underground growing stems). Do not plant St. Augustine in high traffic areas or areas with poor drainage.
Planting St. Augustine grass from sod provides quick lawn coverage and is the preferred method to establish a St. Augustine lawn. Before planting, check the availability of nutrients and soil characteristics through testing. With adequate fertility and drainage, St. Augustine grass tolerates a wide range of soil types including sandy and clay soils. St. Augustine grass grows within a broad pH range—5.0 to 8.5—and accepts soil salinity as high as 16 mmhos (measurement of electrical conductivity) according to Texas A&M Horticulture.
Grade and till the soil and apply amendments, as needed, before laying sod when soil is warm—usually late spring through early fall. Cover the entire area, firm into place with a roller, and water frequently for two weeks until established. In clay soils, watering once per day is sufficient. However, sandy soils with poor moisture retention require several applications per day using smaller amounts of water.
The growth rate of St. Augustine grass is a function of temperature, moisture and nutrient availability. An established turf may require mowing every two weeks in early spring and every five or six days by late spring and summer. Nitrogen fertilizers increase growth rate. Mow St. Augustine when it is 3 inches tall and remove only 1/3 of the growth by setting your mower cutting height to 2 inches. Add fertilizer in the amount and components recommended in your soil test report.
Weeds and Diseases
A hardy stand of St. Augustine chokes out most weeds during its growing season. However, in the dormant period from November through early April, weeds can invade the area. Treat seeded weeds with a pre-emergent herbicide before they emerge and remove broadleaf weeds by hand, if possible. If using a broadleaf herbicide, check the instructions carefully because some broadleaf weed killers also kill St. Augustine grass.
Common St. Augustine diseases include brownpatch, St. Augustine Decline (also called SAD), rust, gray leaf spot, downy mildew and Helminthosporium. Other than SAD, these diseases are caused by fungi and can be controlled with fungicides. There is no chemical control for SAD. If this is a problem in your area, select St. Augustine varieties that are resistant.