St. Augustine

One of the most common and frequently used turf grasses in the Gulf Coast region and coastal areas throughout the world including in Southern Mexico, throughout the Caribbean region, South America, South Africa, Western Africa, Australia and the South Pacific and Hawaiian Islands is St. Augustine. It is a grass that is mainly adapted to wet areas like freshwater swamps and marshes as well as salty shorelines and lagoons. St. Augustine was in its early days a costal grass but gradually moved inland toward stream banks and lakeshores that had relatively open areas. It is adapted well for many soil sites but does not stand up to extremely wet seasons or dry seasons such as droughts. The rest of this page gives a brief summary on the different varieties of St. Augustine, how to plant and maintain a St. Augustine lawn, and problems with the grass.

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Varieties of St. Augustine
  • Bitter-Blue: a good option for shady lawns. Its slow growth rate means you mow less often. Has an improved cold weather tolerance.
  • Delmar: a dwarf St. Augustine cultivar that has good shade tolerance, yet also does well in full sun. A delmar lawn has a tendency to develop heavy thatch.
  • Delta Shade: has good shade tolerance, but not as good as dwarf varieties.
  • Floralawn: has poor shade and cold tolerance; performs best in mild environments
  • Floratam: A popular among Florida homeowners, Floratam is adaptable to many soil conditions and thrives in direct sunlight. Was develped by Texas A&M and Florida.
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  • Palmetto: Good in coastal and island areas and is rapidly being positioned as a standard St. Augustine, having proved itself repeatedly since 1994. Prefers heat but will handle cold better than other types of St. Augustine. Performs well in both full sun and partial shade; has a natural resistance to cinch bugs.
  • Raleigh: somewhat more cold-hardy, but does not hold up to summer heat as well as other St. Augustine's. Has been adapted to grow in heavier, clay-like soils.
  • Sapphire: The only high performance, finer blade St. Augustine. Has a distinctive deep, blue-green color along with a soft texture. Suitable for demanding, warm climates, Sapphire tolerates salt, shade and drought, making it an excellent choice for coastal regions. Requires less fertilization and displays improved recovery from wear, with reduced weed problems.
  • Seville: Blue-green in color with excellent color retention, Seville tolerates salt, shade and drought well. Its long leaf blade gives it a unique appearance preferred by many homeowners

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Most varieties of St. Augustine grass are sterile and so since it was first cultivated, it has been propagated by vegetative means which means using stolons, plugs or sod. Recently however a seed propagation has been developed for St. Augustine grass and is being used. However significant usage has not been made in this area. As reported by Long and Bashaw at Texas A&M in 1961 only a few strains of St. Augustine grass are fertile. The common strain of St. Augustine grass found in Texas is generally fertile; whereas, the strains used in Florida since before 1900 were found to be sterile.

Sod is the most common form of establishment for the vigorous St. Augustine grass because it spreads rapidly by creeping stolons. Sod production of St. Augustine is a large industry in the Southern coastal states but Florida is the leader. Commercially St. Augustine grass is produced in 300 to 500 square yard bushels per acre.
St. Augustine grass can also be established by spacing sod plugs( 2 to 4 square inch) or stolons cultivated from sod 1 to 2 feet from each other and can be expected to cover the whole lawn in one growing season. St. Augustine grass can be successfully established from plugs anytime during the growing season if water is available. Unlike bermudagrass, St. Augustine grass is not effectively propagated from stolons. St. Augustine grass stolons are much more prone to desiccation than bermudagrass. Also, bermudagrass roots much faster and has a faster growth rate than St. Augustine grass. As a result, St. Augustine grass is not successfully established by hydromulching or broadcasting stolons.
If you are trying to establish a lawn of St. Augustine grass by seed you will need to plant at least 1/3 to ½ pound of PLS per 1,000 square feet. The establishment from seed planting would be about the same as propagation from plugs planted in 1 foot spacing and a seeded St. Augustine grass lawn should be watered immediately and watered regularly for the next few weeks following planting to get maximum results and get a nice stand of grass. St. Augustine grass can start to tolerate dry conditions after the seedlings have begun to spread. St. Augustine grass should be planted in late spring to early summer to achieve satisfactory results.
During the establishment period (1st three months after planting), fertilization is critical to develop a complete cover of a St. Augustine lawn. A good starter fertilizer (one high in phosphorous) or a balanced, complete fertilizer should be applied at planting time. Reapply nitrogen at subsequent monthly intervals at a rate of one pound per 1,000 square feet to promote rapid growth and spread of St. Augustine plugs. To control weeds on a new St. Augustine lawn use asulam (Asulox) and hormone-type herbicides (2,4-D, MCPP, dicamba) to stop preemerge and post emerge weeds.

St. Augustine
St. Augustine

Problems with St. Augustine

One problem that St. Augustine Grass can have is iron chlorosis, or lack of iron. This most frequently occurs in alkaline soils (pH of above 7.0). The optimum pH range for St. Augustine is 5.5 to 7.2. The pH of the soil affects nutrient uptake, not just for iron, but for a wide range of macro and micro nutrients in the soil. With St. Augustine, if you are having growth or color problems, try testing the pH before adding anything to the soil.
If the pH of the soil is too high, you can add sulfur to the soil. Lawn and garden centers will have products specifically for lawn care. If you have corrected the pH and the grass blades are not dry, but are a yellow color, that is a sign that you need to use a foliar iron spray on the grass. (Foliar means it sticks to and is absorbed through the plant leaves.)

Chinch Bugs

The Southern chinch bug is the most important insect pest of St. Augustine grass in Florida. (Figure 1) It does not affect any other coastal grass as seriously as it does St. Augustine. Beginning in March and April, the eggs of the Chinch bug begin hatching and there are 3-4 generations per year. The immature chinch bugs (nymphs) are about the size of a pinhead and are bright red with a white band across the back. Late stage nymphs and adult chinch bugs are about 1/5 inch long and black. The adults have white wings. Chinch bugs suck the plant juices from grass, this is their main source of food, and also apparently causes other injury to the grass, resulting in yellowish to brownish patches in the lawns.

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Gray Leaf Spot

Gray Leaf Spot is a Pathogen that goes by the scientific name of Pyricularia grisea. This disease has common occurrences in damp lawns. This disease of St. Augustine grass is most often observed from late spring to early fall, especially during prolonged periods of rainfall. Excessive applications of quick-release nitrogen sources enhance disease severity, as does compacted soil. Application of the herbicide atrazine increases the susceptibility of St. Augustine grass to this disease. Small pinhead size spots that are olive-green to brown in color are the initial symptoms. These enlarge and form circular to oblong spots that are tan to brown colored with distinctive dark brown margins. The fungus produces abundant spores in the center of these spots under humid conditions, giving them a velvety-gray appearance. external image gray%20leaf%202.jpg