St. Augustine grass (Stenotaphrum) is a popular warm-season turfgrass for home lawns. It is found in the United States, southern Mexico, South America, South Africa, western Africa, the Caribbean, the Hawaiian Islands, Australia and the South Pacific. St. Augustine grass is medium to dark green and coarse textured, and it has a low, dense growth habit. It grows well in nearly all soil types and tolerates shade, heat, salt and, to some degree, drought. It does not tolerate waterlogged soils or extended periods of cold weather. St. Augustine grass is an aggressive species that spreads rapidly by above-ground growth structures called stolons. If managed properly, St. Augustine grass forms a dense cover that handles light traffic and competes well with most weeds. St. Augustine grass is the most shade tolerant warm-season turfgrass. Texas Common, Raleigh, Seville, Palmetto and Floratam are St. Augustine varieties commonly used for home lawns in the southern United States. Each variety has characteristics that make it best in certain situations. Contact your county Extension agent for information on the variety best suited for your location. To keep your St. Augustine grass lawn in good condition, follow these guidelines for mowing, watering and fertilizing, as well as for controlling weeds, insects, thatch, and eliminating compacted soil. Because many factors affect turf growth, these are general recommendations.
MARCH through May Mowing Begin a routine mowing program as soon as the grass begins to turn green in the spring. Remove no more than one-third of the leaf area with any one mowing. Set the mowing height at 21 /2 to 3 inches (3 to 31 /2 inches in shady lawns). The lower the mowing height, the more frequently you will need to mow. Frequent mowing at a lower height produces higher quality turfgrass. It is best not to bag grass clippings. Grass clippings decompose quickly and return significant amounts of nutrients to the soil. If you do bag the clippings, consider composting them for use in the landscape. Fertilizing Begin fertilizing 3 weeks after the grass turns green and when there is little chance of a late frost. Apply 1 pound of soluble nitrogen per 1,000 square feet of lawn every 8 weeks, or 11 /2 pounds of slow-release nitrogen every 10 weeks.
Have your soil tested to determine what added nutrients your lawn may need. For information on soil testing procedures, contact your county Extension agent. If you do not have the soil tested, use a complete fertilizer with a 3-1-2 ratio of nitrogen, phosphorus and potassium (Examples: 15-5-10, 21-7-14, etc. Every bag of fertilizer has the nutritional analysis printed on the bag). To determine the amount of fertilizer needed to equal 1 pound of nitrogen per 1,000 square feet, divide 100 by the first number in the fertilizer analysis. For example, if you are using a 15-5-10 fertilizer, then you need 6.6 pounds per 1,000 square feet. (To determine the amount needed to apply 11 /2 pounds per 1,000 square feet, substitute 150 for 100.) 100 15 = 6.6 Then determine the size of the area to be fertilized. If your lawn is 5,000 square feet, you will need 33 pounds of 15-5-10 fertilizer. (5,000 1,000) x 6.6 = 33 pounds of fertilizer Watering To keep your lawn healthy, water it only when the grass needs it. When you do water, wet the soil to a depth of 6 inches. Then don’t water again until the grass shows symptoms of drought stress—a dull, bluish color, rolled or folded leaves, and persistent footprints.
This usually occurs in 5 to 10 days, depending on the weather. Follow these steps to determine how long to water to apply the right amount. 1. Set out five or six open-top cans randomly around the lawn (tuna or cat food cans work best). 2. Turn on the sprinklers or irrigation system for 30 minutes. 3. Using a ruler, measure the depth of water caught in each individual can, and record the depths. 4. Calculate the average depth of water of all the cans. Example: You have placed five cans in your yard. The depths of water in the cans were 0.5 inch, 0.4 inch, 0.6 inch, 0.4 inch and 0.6 inch. Add the depths together and divide by the number of cans you used. 0.5 + 0.4 + 0.6 + 0.4 + 0.6 = 2.5 inches 2.5 inches 5 cans = 0.5 inch of water in 30 minutes New-style irrigation controllers allow you to water several times a day, so you can program them to prevent run-off. 5. Use a garden spade or a soil probe to find out how deeply the soil was wet during the 30-minute period. The probe will push through wet soil easily, but it is more difficult to push through dry soil. With proper maintenance, you can help keep your St. Augustine grass lawn healthy and attractive. St. Augustine grass spreads by above-ground growth structures called stolons.
When you know how much water was applied in 30 minutes and how deeply that volume of water wet the soil, then determine how long you must water to wet the soil to a depth of 6 inches. Example: If the sprinklers sprayed 1 /2 inch of water in 30 minutes and wet the soil to a depth of 3 inches, you would need to apply 1 inch of water to wet the soil to a depth of 6 inches. To do so you must water for 1 hour. Run-off from watering a lawn can waste a significant amount of water, which is costly and a poor use of a limited natural resource. The factors determining how quickly run-off occurs are the type of soil and the application rate of the sprinkler system. Do not apply water faster than the soil can absorb it. To prevent run-off: 1. Check the lawn while watering. If water begins running into the streets or gutters, note how long it took before run-off occurred. This is the maximum amount of time you should water at one time. 2. Stop watering and allow the soil surface to dry (30 minutes to 1 hour). 3. Begin watering again and continue for the time you’ve determined.
With an automatic irrigation system, change your timer to the new, shorter time. 4. Continue this cycle until the appropriate amount of water has been applied to wet the soil to a depth of 6 inches. Controlling weeds The best form of weed control is a healthy, dense, actively growing lawn. To control crabgrass and other grassy weeds, apply preemergent herbicides (which control weeds before they sprout from the ground) in the spring when soil temperature reaches 65 ºF or when the redbud and dogwood trees begin to bloom. Apply postemergent herbicides (which control weeds that have already sprouted) as needed. Apply herbicides only when weeds are present, and when the grass is healthy and actively growing. Weed control is most effective if you apply the herbicide when the weeds are still very small. St. Augustinegrass is very sensitive to some herbicides, such as 2,4-D. Read the label carefully before applying any herbicide to ensure that it is the right product for the weeds you have and that you do not damage the turf. Follow all instructions on the label. It explains how and when to use the product and how much to apply.
Controlling insects Chinch bugs and white grubs are the two most serious insect pests in St. Augustine grass lawns. Routinely check for these pests and treat as necessary. (See L-1766, “Chinch Bugs in St. Augustine Lawns,” and L-1131, “White Grubs in Texas Turfgrass,” available from the Texas Agricultural Extension Service.) Controlling thatch If the thatch layer (a layer of undecomposed plant matter) is more than 3 /4 inch thick, mow the lawn with a vertical mower or scalp the lawn (cut with a rotary mower at its lowest setting) in April or May when the grass is healthy and actively growing. Eliminating compacted soil In areas of heavy traffic, aeration can help eliminate compacted soils. Use a core-aerating machine when the grass is actively growing. If you have an underground irrigation system, flag the sprinkler heads first to avoid damaging them. JUNE through September Mowing Follow the same recommendations as for March through May. Fertilizing Continue the fertilizer program begun in the spring, applying 1 to 11 /2 pounds of nitrogen per 1,000 square feet every 8 to 10 weeks. Without soil test information, it is recommended that you use a fertilizer that either contains nitrogen only (21-0-0, ammonium sulfate) or is low in phosphorus (Examples: 21-3-6 or 15-0-15) to reduce the chance of excessive phosphorus Frequent mowing at a low mowing height produces a higher quality turfgrass.
Produced by Agricultural Communications, The Texas A&M University System Extension publications can be found on the Web at: http://agpublications.tamu.edu Educational programs of the Texas Agricultural Extension Service are open to all people without regard to race, color, sex, disability, religion, age or national origin. Issued in furtherance of Cooperative Extension Work in Agriculture and Home Economics, Acts of Congress of May 8, 1914, as amended, and June 30, 1914, in cooperation with the United States Department of Agriculture. Chester P. Fehlis, Deputy Director, Texas Agricultural Extension Service, The Texas A&M University System. 5 M, New TURF 4 build-up in the soil. Such build-ups can lead to deficiencies in iron and zinc. To prevent yellowing caused by iron chlorosis, apply liquid or granular iron fertilizer throughout the growing season. Follow the label directions for the rate of application. Fertilizers containing iron may stain concrete, brick or stone surfaces. Watering Follow the same recommendations as for March through May. Controlling weeds Continue applying postemergent herbicide as needed. Herbicides containing 2,4-D should be used with care, as St. Augustinegrass is sensitive to this herbicide.
Herbicides may damage the lawn if you apply them when the temperature is higher than 90 ºF. Controlling insects Follow the same recommendations as for March through May. The most effective time to treat for white grubs is in August when they are immature and close to the soil surface. Eliminating compacted soils Follow the same recommendations as for March through May. SEPTEMBER through February Mowing Continue the recommended mowing practices until the grass goes dormant and does not require mowing. Fertilizing Continue fertilizing as recommended until 4 to 6 weeks before the first expected frost. At that time, apply a low nitrogen, high-potassium fertilizer such as 5-10-10. Apply no more than 1 /2 pound of nitrogen per 1,000 square feet. To calculate the amount of product needed per 1,000 square feet, substitute 50 for 100 in the spring formula.