St. Augustinegrass for Florida Lawns¹

St. Augustinegrass (Stenotaphrum secundatum [Walt.] Kuntze.), is widely adapted to the warm, humid (subtropical) regions of the world. It is believed to be native to the coastal regions of both the Gulf of Mexico and the Mediterranean. In Florida, St. Augustinegrass is the most commonly used lawngrass throughout the state. It can grow satisfactorily in a wide variety of soils.

Figure 1. St. Augustinegrass.

Advantages

Disadvantages

St. Augustinegrass, like most turfgrasses, has certain cultural and pest problems. It does not remain green during drought conditions without supplemental irrigation. It produces thatch under high fertilization and irrigation regimes. It has poor wear tolerance and will generally not stay green throughout the winter months in many parts of the state. The coarse leaf texture of most cultivars is objectionable to some people. The major insect pest of St. Augustinegrass is the chinch bug, and there are currently no chinch bug resistant cultivars available. Grubs can also be a major insect pest. Some cultivars are also susceptible to diseases such as gray leaf spot, brown patch, take-all patch, and root rot. Additionally, there are no herbicides available to control hard-to-kill grass-type weeds that may become established in the turf.

Cultivars

There are several cultivars of St. Augustinegrass available for lawn use in Florida. The different cultivars vary in their tolerances to environmental stresses and susceptibility to pests.

'Floratam'

'Floratam' is an improved St. Augustinegrass that was released jointly in 1973 by the University of Florida and Texas A & M. 'Floratam' is the most widely produced and used St. Augustinegrass in Florida. It is a coarse-textured cultivar that has poor cold and shade tolerance relative to other St. Augustinegrass cultivars. It will not persist well in environments that receive less than 6 hours of sunlight daily. It grows vigorously in warm weather, but has a relatively long period of dormancy in north Florida and greens up more slowly in the spring than some cultivars. When first released, it had UF-documented chinch bug resistance, although that has largely been lost over time and chinch bugs are now a major pest of 'Floratam'. It is also susceptible to gray leaf spot and other diseases. 'Floratam' is intolerant of atrazine herbicides when temperatures are above 85°F. It is a "standard" cultivar and should be mowed at 3.5 to 4 inches. 'Floratam' is available as a certified cultivar

'Bitterblue'

'Bitterblue' is a variety that was selected in the 1930s. Although 'Bitterblue' is marketed as a certified cultivar, there is no certified 'Bitterblue' germplasm maintained by turfgrass breeders at this time. What is typically sold as 'Bitterblue' has a fine, dense texture and dark blue-green color. It has good cold and shade tolerance, but is not resistant to chinch bugs or gray leaf spot disease. It is also susceptible to the herbicide atrazine, making weed control difficult. It is what is referred to as a "standard" cultivar, with a mowing height of 3.5 to 4 inches.

'Palmetto'

'Palmetto' was a selection found by a Florida sod grower in 1988 and was released in the mid 1990s by Sod Solutions. It is of intermediate growth, with shorter leaf blades and internodes than many other cultivars, but is slightly larger than the dwarf St. Augustinegrass cultivars such as 'Seville' and 'Delmar'. It has a nice growth habit and does well in full sun or partial shade, but not in dense shade. It is sometimes referred to as drought-tolerant, but research has not shown that it has any greater degree of drought tolerance than other St. Augustinegrasses. It often has problems with disease, particularly in Florida's humid environment. It tends to have a lighter green color than many other cultivars.

'Seville'

'Seville' is a dwarf, fine-leaved variety with a dark green color and a low growth habit. It is susceptible to chinch bug and webworm damage. Like the other dwarf cultivars, 'Seville' tends to be thatch-prone. 'Seville' performs well in both shade and full sun, but is cold-sensitive. 'Seville' should be mowed at 2 to 2.5 inches. 

Maintenance of St. Augustinegrass

Proper lawn maintenance practices are the best means for avoiding pest problems and obtaining a high-quality lawn.

St. Augustinegrass will require inputs of fertilizer to maintain a nice green color and healthy growth characteristics. During certain times of the year, it may require irrigation, however, this may not be the case year round. Pesticides may be needed periodically, but their use can be minimized if other cultural practices (mowing, irrigation, fertilization) are done correctly.

Establishment

Although St. Augustinegrass can be planted year-round in warmer sections of Florida, the best time to plant is when environmental conditions allow for rapid establishment. Allowing the grass to establish and develop a deep root system before it experiences temperature extremes will help it establish more quickly and with less water. 

It is important to provide frequent irrigation when grass is establishling. Multiple, short irrigations throughout the course of the day for 7 to 10 days following planting will help the grass establish. After the roots have pegged down, cut back frequency to once a day and increase the time to 1/4 to ½ inch for another 7 days. After this, reduce frequency to 2 to 3 times weekly, again applying ¼ to ½ inch of water. Three to 4 weeks after sodding, the grass should be fully established and irrigation can begin on an "as-needed" basis. For more information on this, see ENH 860 "Irrigation and Fertilization Requirements of Lawns and Landscapes."

Do not mow the lawn until the roots have had a chance to peg down into the soil, generally about 10 to 14 days after planting. Pegging means that the sod cannot be lifted without appreciable force. For more information on preparing the site and establishment, refer to ENH03 "Establishing Your Florida Lawn."

St. Augustinegrass is established by vegetative propagation such as sod, plugs, or sprigs. Vegetative propagation means that instead of seeds, plant parts with growing points are used for planting. St. Augustinegrass has stolons (above-ground stems) that have areas of actively dividing cells at the nodes. These areas are capable of generating new shoot growth and are responsible for lateral growth of St. Augustinegrass along the ground.

Mowing

Proper mowing practices are necessary to keep any lawn healthy and attractive. Standard St. Augustinegrass cultivars ('BitterBlue', 'Classic', 'Floratam', 'Floratine', 'Palmetto', etc.) should be maintained at a height of 3.5 to 4 inches. Repetitively mowing at lower heights reduces overall stress tolerance of the lawn, discourages deep rooting, increases the chance for scalping if a mowing event is missed or postponed due to weather, and may increase susceptibility to pest problems. To obtain the correct height with most home rotary lawn mowers, use the highest wheel height setting. Maintaining the right height will help the grass develop a deep root system and give a better appearance to the turf. No more than a third of the leaf blades should be removed with any mowing. If possible, increase mowing height during periods of moisture stress or if the grass is growing in shade. Newer semidwarf varieties have a lower growth habit, and should be mowed at 2 to 2.5 inches for optimum quality. Mowing too infrequently and watering improperly can cause a thatch buildup.

Grass clippings should be left on a lawn that is mowed at the proper height and frequency. Under these conditions, clippings do not contribute to the thatch layer. Clippings put nutrients back into the soil system and may reduce turf fertilization requirements by up to 25%. If clippings are excessive (e.g., clumping occurs), let them dry out and then disperse them over the lawn.

Watering

The best way to irrigate an established lawn is on an as-needed basis. Grass blades will begin to wilt (e.g., fold, turn bluish-green in color, and not recover from traffic or footprints) as the moisture begins to be depleted in the soil. If the lawn shows signs of slight wilting, it is time to irrigate with ½ to ¾ inch of water. Do not water again until the lawn shows signs of wilting. The amount of water applied should not vary, but the frequency with which your lawn needs water can vary due to season, soil type, grass species, temperature, etc. For further information on recommended watering practices, refer to ENH9 "Watering Your Florida Lawn" and ENH63, "Let Your Lawn Tell You When to Water."

Proper watering practices will help maintain a lawn that requires less mowing and has little thatch buildup. Proper watering will also help develop a deep root system and make the lawn less susceptible to damage by pests and environmental stresses. If the diseases brown patch or gray leaf spot are a continuous problem, excessive watering and nitrogen fertilization may be responsible. Certain weeds, such as dollarweed and sedges, also thrive in soils that are continuously wet.

Figure 8. Let your lawn tell you when to water. Look for folded leaf blades as seen here.

Pest Problems

Other factors can also decrease the quality of a lawn. Excessive shade, compacted soils, overwatering, improper mowing, traffic, and high or low pH can all cause a lawn to perform poorly. It is important to recognize what the source of the problem is and to correct it if possible. For more information on these types of stresses, refer to ENH153, "Environmental Stresses and Your Florida Lawn."

Weeds

The best approach to weed control is a healthy, vigorous lawn. Weed problems in a lawn indicate that the turf has been weakened by improper management practices or damage from pests. Proper management practices can eliminate most weed problems. If weeds are a persistent problem, herbicides labeled specifically for St. Augustinegrass should be used. If an herbicide is needed, apply preemergence herbicides (i.e., pendimethalin, benefin, bensulide, atrazine, or others) to control crabgrass if it was present in previous years. Timing is critical for successful control. As a general rule, apply Feb. 1 in south Florida, Feb. 15 in central Florida, and March 1 in north Florida. Note: Preemergence herbicides will not control weeds that are actively growing.

Apply postemergence herbicides (e.g., atrazine) as needed for control of summer annual and perennial broadleaf or grassy weeds. Do not apply these materials if the turf is under moisture stress or if air temperatures exceed 85°F. Check with your local county cooperative extension office for positive weed identification and latest recommendations.

Many commercial "weed-n-feed" formulations will provide control, but they should be used with caution because certain plant materials may not be tolerant. These herbicides can damage landscape plants whose roots may extend far under the lawn. Carefully read the label before use and follow all label directions. Refer to ENH884, "Weed Management in Home Lawns" for more information.

Insects

The major pest of St. Augustinegrass is the chinch bug . These are foliar-feeding insects that suck plant juices through a needlelike beak, causing yellowish to brownish patches in turf. Injured areas are usually first noticed as the weather begins to warm, in areas along sidewalks, adjacent to buildings, and in other water-stressed areas where the grass is in full sun.

CREDITS: Eileen Buss, UF/IFAS

Figure 9. Chinch Bug Damage.

Check for chinch bugs by removing the ends of a coffee can, inserting one end into the soil at the margin of suspected damaged areas, and filling with water. Chinch bugs will float to the water surface within five minutes. In areas where chinch bugs are a serious problem, a single, thorough insecticide treatment may offer only temporary control. Therefore, repeat applications may be required. Some populations of this insect have become resistant to synthetic pyrethroid insecticides.

CREDITS: James Castner, UF/IFAS

Figure 10. Adult chinch bugs.

Other insect pests, including webworms, armyworms, grass loopers and mole crickets can damage St. Augustinegrass. Mole crickets damage turfgrass areas primarily by creating tunnels or soft mounds while searching for food. Additional damage may result from small animals digging through the soil profile in search of the mole crickets as food. Check for mole crickets by (1) examining an area for the tunnels, or (2) applying 2 gallons of water mixed with 1½ ounces of detergent soap per 2 square feet in suspected damaged areas. Mole crickets will surface in several minutes.

White grubs are another pest of St. Augustinegrass. These can be found by lifting the grass to a depth of about two inches. Grubs will be seen feeding on the roots at this level. For more information on insect control, refer to ENY300, "Insect Pest Management on Turfgrass."

Diseases

CREDITS: Phil Harmon, UF/IFAS

Figure 11. Brown Patch symptoms on St. Augustinegrass.

Brown patch and gray leaf spot are two major disease problems of St. Augustinegrass. Brown patch occurs in warm, humid weather and is encouraged by excessive nitrogen. Brown patch is generally most noticeable during spring and fall months. Gray leaf spot occurs during the summer rainy season and is primarily a problem on new growth. Both diseases can be controlled with fungicides.

CREDITS: Phil Harmon, UF/IFAS

Figure 12. Grey Leaf Spot symptoms on St. Augustinegrass.

Other St. Augustinegrass disease problems originate in the root system. Take-all root rot (Gaeumannomyces graminis var. graminis) occurs under high moisture or stress conditions. When symptoms are noticeable aboveground, the disease is usually in an advanced state. Following proper cultural practices is the best defense against this disease. Refer to SS-PLP-14, "Turfgrass Disease Management" for more information.

Nematodes

Several types of nematodes infest St. Augustinegrass lawns. Population peaks of nematodes typically occur in late April to early May and again in late August to early September. Damage symptoms include thin stand density, less vigorous growth, a weakened root system, slow recovery following rain or irrigation application, and certain weed invasions (e.g., prostrate spurge and Florida pusley). Soil nematode levels can only be positively identified through laboratory procedures. Your local county Extension service office can provide information on submitting soil samples to the University of Florida Nematode Assay Laboratory. There are currently no effective nematode controls for use in the home lawn. Cultural controls include encouraging deep turfgrass rooting by raising the mowing height, irrigating less frequently but more deeply, and providing ample soil potassium. For more information on nematodes, refer to ENY006, "Nematode Management in Residential Lawns."

CREDITS: William Crow

Figure 13. Signs of nematode damage in St. Augustinegrass.

Other Problems

Many other factors can decrease the quality of a lawn. To ensure a good St. Augustinegrass lawn, refer to other sections of this publication for recommended management practices, and follow label directions when applying fertilizers and pesticides.

Thatch Removal

Thatch is the layer of undecomposed leaf blades, stolons, roots, and crowns intermingled with soil. Leaving mowing clippings on the lawn does not cause thatch because clippings are readily broken down by microbes in the soil. Thatch development is greatest in grass that is overfertilized, overwatered, and improperly mowed. An excessive thatch layer will reduce water penetration and can bind up fertilizer or pesticides. In severe cases, you may see roots actually growing above ground and rooting into the thatch layer. This is a very unhealthy condition and leaves a lawn vulnerable to many stresses.

Figure 14. Thatch layers can develop in St. Augustinegrass, especially when fertilization or irrigation rates are high.

If the thatch layer exceeds 1 inch, remove by vertical mowing, or "verticutting" in early spring to mid summer. Verticutting uses vertical blades that slice through the thatch and slightly into the soil, which results in much of the dead material being removed to the top of the lawn. A 3-inch spacing between the de-thatching blades is best for St. Augustinegrass. Caution: Vertical mowing may result in damaged turf that will require a period of recuperation. Do not attempt vertical mowing unless the grass is actively growing. Verticut in an east to west or north to south pattern but not in all four directions. A professional landscaping maintenance service or the local county cooperative extension service office should be consulted before attempting lawn renovation. Remove debris by raking, sweeping, or vacuuming, and follow with a conventional mowing to improve turf appearance. Immediately irrigate to prevent root zone dehydration. One week after vertical mowing, apply 1/2 pound of soluble nitrogen per 1000 square feet to encourage recovery. This material must be watered into the soil immediately following application to prevent plant burn. Periodic topdressing (adding a uniform layer of soil on top of the grass) with ¼ inch of soil similar to that underlying the turf is the best method to alleviate thatch accumulation; however, the physical labor required limits the practicality of this method for most homeowners. If topdressing, be sure to use soil that is free of weed seeds and nematodes. Do not exceed recommended topdressing rates, as this encourages brown patch disease.

Footnotes

1. This document is Fact Sheet ENH5, a series of the Environmental Horticulture Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. First published: May, 1991. Revised: October, 2000; June, 2006. Please visit the EDIS website at http://edis.ifas.ufl.edu.

2. L.E. Trenholm, Associate Professor, Turfgrass Specialist, Department of Environmental Horticulture, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611, J.B. Unruh, Associate Professor, Turfgrass Specialist, West Florida Research and Education Center, Institute of Food and Agricultural Sciences, Jay, FL 32565, and J.L. Cisar, Professor, Turfgrass Specialist, Ft. Lauderdale Research and Education Center, Institute of Food and Agricultural Sciences, University of Florida, Ft. Lauderdale, FL 33314.

The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.