St. Augustine Grass or Buffalo Grass (Stenotaphrum secundatum) (also known as Charleston Grass in South Carolina) is a warm season lawn grass that is popular for use intropical and subtropical regions. It is a medium to high maintenance grass that forms a thick, carpetlike lawn, crowding out most weeds and other grasses.
Annual Maintenance Schedule
March Through May
Mowing: St. Augustinegrass performs best when mowed between 2 and 4 inches depending on the cultivar. The normal growth cultivars like Raleigh should be mowed between 3 and 4 inches, while the semi-dwarf growth habit cultivars such as Palmetto and Mercedes can be mowed between 2 and 3 inches. Begin mowing as soon as the lawn turns green in spring. Always leave the clippings on the lawn in a practice called ‘grass-cycling’. If prolonged rain or other factors prevent frequent mowing and clippings begin to clump, they can be collected and used as mulch. Never remove more than ⅓ of the leaf tissue in any single mowing. For more information on mowing lawns refer to HGIC 1205, Mowing Lawns.
Fertilizing: St. Augustinegrass performs best when fertilized with 2 to 4 pounds of nitrogen (N) per 1,000 square feet per year depending on location, health of lawn, soil type, and many other factors. In spring, apply ½ to 1 pound of N per 1,000 square feet several weeks after the last expected frost. Submit a soil sample to determine nutrient and lime requirements. In the absence of a soil test, use a complete (N-P-K) turf-grade fertilizer with a 4-1-2 ratio such as 16-4-8. Apply lime if suggested.
To determine the amount of product needed to apply ½ pound of N per 1,000 square feet, divide 50 by the first number in the fertilizer ratio. For example, for a 16-4-8 fertilizer, divide 50 by 16. The result is 3.125 pounds of product per 1,000 square feet: 50/16 = 3.125 pounds of 16-4-8 per 1,000 sq. ft. For more information on fertilizing lawns refer to HGIC 1201, Fertilizing Lawns.
Irrigation: As a general rule, irrigate when 30 to 50% of the lawn shows sign of wilt. Probe with a screwdriver to ensure the top 4 to 6 inches of soil are moist following irrigation. Do not irrigate again until the lawn shows sign of wilt. In general, St. Augustinegrass needs a total weekly application of about 1 inch of water. Sandy soils often require more frequent watering, for example, ¾-inch of water every third or fourth day. For more information on watering lawns refer to HGIC 1207, Watering Lawns.
Weed Control: Apply preemergence herbicides to control summer annual weeds when forsythia or redbuds are in full bloom. Apply postemergence herbicides in May as needed to control summer annual and perennial broadleaf weeds. Be sure that the product is labeled for use on St. Augustinegrass. Apply postemergence herbicides when weeds are present, and at least three weeks after the lawn greens up. For more information on weed control refer to HGIC 2310, Managing Weeds in Warm Season Lawns.
Thatch Removal: Vertically mow in May to remove the thatch after the lawn becomes green and is actively growing, but only if the thatch is more than ½-inch thick. A 3-inch spacing between the blades is best for St. Augustinegrass. After dethatching, irrigate with ¾ to 1 inch of water. Fertilize with 1 pound of N per 1,000 square feet if the lawn has not already received a spring fertilization.
Renovation: Replant large bare areas using sod or sprigs (3 to 5 bushels per 1,000 square feet).
June Through August
Mowing: St. Augustinegrass performs best when mowed between 2 and 4 inches depending on the cultivar. The normal growth cultivars like Raleigh should be mowed between 3 and 4 inches, while the semi-dwarf growth habit cultivars such as Palmetto and Mercedes can be mowed between 2 and 3 inches.
Fertilizing: Apply ½ to 1 pound of N per 1,000 square feet every 4 to 8 weeks with a slow release type fertilizer. Slow release fertilizers help reduce problems with chinch bugs.
Irrigation: As a general rule, irrigate when 30 to 50% of the lawn shows sign of wilt. In general, St. Augustinegrass needs a total weekly application of about 1 inch of water.
Insect Control: Chinch bugs are a major pest of St. Augustinegrass and are often misdiagnosed as drought damage. Use a water flotation technique to determine if chinch bugs are present. For details on the flotation technique, see EIIS/TO-20, Chinch Bugs. August is the best time to control white grubs because they are small and close to the soil surface. Mole crickets hatch in early summer and begin to cause noticeable damage by August. Use a soap flush technique to determine if mole crickets are present. For details on the soap flush technique, see EIIS/TO-1, Mole Cricket Management for the Home Lawn.
Weed Control: Apply postemergence herbicides as needed to control summer annual and perennial weeds.
Disease Control: Irrigate properly; overirrigation promotes disease. For more information on disease control refer to HGIC 2152, Leaf Diseases of Lawns.
Thatch Removal: Vertically mow to remove the thatch if it is more than ½ inch thick. It normally is best to vertically mow in spring whenever possible.
September Through November
Mowing: Mow the lawn at the recommended height until several weeks before the first expected frost. Raise the mowing height by one-half inch as winter approaches. Mowing height is usually raised in mid- to late September in the Piedmont and early October in other areas.
Fertilization: Do not apply nitrogen to St. Augustinegrass after the end of August. In sandy soils or when soil tests report deficient potassium (K) levels, apply 1 pound of potash (K2O) using muriate of potash (0-0-60), potassium sulfate (0-0-50), or Sul-Po-Mag (0-0-22).
Irrigation: As a general rule, irrigate when 30 to 50% of the lawn shows sign of wilt. In general, St. Augustinegrass needs a total weekly application of about 1 inch of water. Dormant St. Augustinegrass may need to be watered periodically when warm, windy weather prevails.
Weed Control: Apply preemergence or post-emergence herbicides as needed to control winter annual and perennial broadleaf weeds. Preemergence herbicides do not control existing perennial weeds. Apply postemergence herbicides only when weeds are present.
Insect Control: Continue to monitor for white grubs and control if necessary.
Disease Control: Irrigate properly; overirrigation promotes disease. Fall is the best time of year to control large patch.
December Through February
Mowing: Dormant St. Augustinegrass need not be mowed.
Irrigation: Dormant St. Augustinegrass may have to be watered periodically to prevent drought damage, especially when warm, windy weather prevails. Watering is particularly important for lawns that have been overseeded.
Weed Control: Apply broadleaf herbicides as needed to control winter weeds such as chickweed, henbit, and hop clover. Selective herbicides can be applied in November or December to lawns that have not been overseeded to control annual bluegrass (Poa annua) and several winter annual broadleaf weeds.