St. Augustine grass (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. St. Augustine grass is the most commonly used lawn grass in Florida.
St. Augustine grass produces a green to blue-green dense turf that is well adapted to most soils and climatic regions in Florida. It has relatively good salt tolerance, and certain cultivars have better shade tolerance than other warm-season grass species. St. Augustine grass establishes quickly and easily and may be planted as sod, sprigs, or plugs.
St. Augustine grass, like most turf grasses, has certain cultural and pest problems. It requires water to remain green and healthy and may require supplemental irrigation during extended dry periods. It has poor wear tolerance and does not hold up to repeated foot or vehicular traffic. It goes into winter dormancy in parts of the state and turns a brown or tan color until springtime. It produces thatch under high fertilization and irrigation regimes, which may become a health problem for the grass. It has coarse, wide leaves and stems and therefore does not grow as densely as some other species. The major insect pest of St. Augustine grass is the southern chinch bug (Blissus insularis Barber), which can cause considerable damage if not treated. Some cultivars are also susceptible to diseases, such as gray leaf spot (Pyricularia grisea), large patch (Rhizoctonia solani), and take-all root rot (Gaeumannomyces graminis var. graminis). Chemical weed control can be challenging, particularly when trying to control persistent, grassy weeds, for which there are few herbicide options for use on home lawns.
There are several cultivars of St. Augustine grass available for use in Florida. The different cultivars vary in their tolerances to environmental stresses and susceptibility to pests. St. Augustine grass cultivars can be grouped by their mowing height requirement and leaf texture. Standard cultivars should be mowed at 3.5–4 inches and dwarf cultivars should be mowed at 2.5 inches.
'Bitter blue' was selected in the 1930s. Bitter blue has a relatively fine, dense texture and dark blue-green color. It has good cold and shade tolerance and is well adapted for use throughout the state. It should be mowed to a height of 3.5–4 inches.
'Classic' is a proprietary cultivar released in the early 2000s by Woerner Turf. It has good cold tolerance and is used throughout Florida and other states. Shade tolerance has not yet been verified by university research, and there is no evidence that it is superior to other cultivars. It should be mowed to a height of 3.5–4 inches. It has a dark green color.
'Delta Shade' is a proprietary release from Environmental Turf in 2005. University research shows that 'Delta Shade' has good shade tolerance, but not as good as the dwarf varieties. It appears to have good cold tolerance, although no university studies have been done to verify this. In some landscapes, it tends to have a lighter green color than some cultivars. It should be mowed to a height of 3.5–4 inches.
'Floratam' is an improved St. Augustine grass that was released jointly in 1973 by the University of Florida and Texas A & M University. 'Floratam' is the most widely produced and used St. Augustine grass in Florida. It is a coarse-textured cultivar that has poor cold and shade tolerance relative to other St. Augustine grass cultivars. It does not persist well in environments that receive less than 6 hours of sunlight daily. It grows vigorously in the spring and summer. 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 also is susceptible to gray leaf spot and other diseases. 'Floratam' is not tolerant of herbicides that contain atrazine when applied at temperatures above 85°F. It should be mowed to a height of 3.5–4 inches.
'Palmetto' was a selection found by a Florida sod grower in 1988 and released in the mid-1990s. It is sometimes referred to as a "semi-dwarf cultivar" with a shorter growth habit and internodes than many other cultivars, but it is slightly larger than the dwarf St. Augustine grass cultivars. It 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. Augustine grass cultivars. It is not resistant to insects and sometimes has problems with disease, particularly in Florida's humid environment. It tends to have a lighter green color than many other cultivars. It should be mowed to a height of 3–4 inches.
'Raleigh' is a cold-hardy cultivar released by North Carolina State University in 1980. It has a medium green color and a coarse texture. It is susceptible to chinch bugs and large patch disease, but is used in northern Florida due to its tolerance to lower temperatures. It is highly susceptible to gray leaf spot. During peak summertime heat, 'Raleigh' has been noted to yellow and grow less aggressively than it does at cooler temperatures. Supplemental iron applications can reduce this yellowing tendency. 'Raleigh' is best adapted to the heavier clay soils with medium to low soil pH of north and northwest Florida.
'Captiva' (Figure 4) was released by the Florida Agricultural Experiment Station in 2007. It has dark green, short, narrow leaf blades and reduced vertical leaf extension, making it a slower-growing cultivar. It exhibits improved tolerance to chinch bugs compared to other commercially available cultivars. It is somewhat susceptible to diseases such as large patch and take-all root rot, particularly if it receives excess fertilizer or irrigation. Although it has not been officially evaluated for shade tolerance, the dwarf St. Augustine grass cultivars all have better tolerance to shade than the standard cultivars. It should be mowed to a height of 2–2.5 inches.
'Delmar' is often sold as sod or plugs. It has good shade tolerance and also does well in full sun. It has short internodes, a dark green color, and good cold tolerance. ‘Delmar’ is susceptible to chinch bugs, tropical sod web worms (Herpetogramma phaeopteralis), and large patch disease. Like the other dwarf cultivars, it has a tendency to become thatchy. It should be mowed to a height of 2–2.5 inches.
‘Sapphire’ has a blue-green leaf color, purple stolon color, and long leaf blades that remain folded, giving the grass a fine leaf appearance. It spreads rapidly and grows aggressively during the growing season. It is susceptible to most major pests associated with St. Augustine grass. ‘Sapphire’ should be mowed to a height of 2–2.5 inches.
‘Seville’ is a fine-leaved variety with a dark green color and a low growth habit. It is susceptible to chinch bug and web worm damage. Like the other dwarf cultivars, ‘Seville’ tends to be prone to thatch. ‘Seville’ performs well in both shade and full sun, but is cold sensitive. It is not as common as ‘Delmar’, but is also a good choice for shady sites. ‘Seville’ should be mowed to a height of 2–2.5 inches.
Establishment of St. Augustine Grass
Although St. Augustine grass can be planted year-round in warmer regions of Florida, the best time to plant any warm-season grass is during its time of active growth for quickest establishment. It is also best to avoid temperature extremes if possible, especially if freezing temperatures are forecast. In south Florida, the optimal time for establishment is late fall, winter, or spring. In central and north Florida, try to avoid establishment during cold winter or hot, dry summer months.
St. Augustine grass is established by vegetative propagation only, which includes sod, plugs, or sprigs. Vegetative propagation means that plant parts with growing points are used for planting rather than seeds. St. Augustine grass has stolons (above ground stems) that have areas of actively dividing cells at the nodes. These areas are capable of generating new shoot and root growth and are responsible for lateral growth of St. Augustine grass along the ground.
It is important to provide irrigation on the correct schedule when grass is newly planted. Multiple, short (5–10 minutes) irrigation's throughout the course of the day for 7–10 days following planting helps the grass establish without drying out. For the next 7–10 days, irrigate once a day to apply ¼–½ inch of water. After this, frequency should be reduced to 2–3 times weekly, again applying ¼–½ inch of water. Three to four weeks after sodding, the grass should be fully established and irrigation can begin on an as-needed basis. For more information, refer to ENH9,
A newly planted lawn should not be fertilized until 30–60 days after planting. Because the root system is not developed on new plantings, fertilizing before this can result in nutrient leaching or runoff and potential pollution of ground or surface waters. Sod is generally fertilized prior to harvest and does not need supplemental nutrients for this time, so the delay in fertilizing will not affect turf health or establishment. The lawn should not be mowed until the roots have had a chance to peg down into the soil, generally 14–21 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,
Sodding is the fastest way to establish a lawn because it provides complete ground cover and it is not necessary to wait for it to fill in. Sodding reduces potential weed competition that can occur when using other planting methods that leave bare ground. However, it is important to remember that the grass is still vulnerable at this stage, and it is not yet safe for play or other activities. It is quite dependent until the roots have developed and extended down into the soil. Sod pieces should be laid over bare, moist soil in a staggered brick-like pattern, and the edges should be fitted tightly together to avoid any open cracks. Rolling and watering thoroughly ensures good contact with the soil for fast rooting. For more information on preparing the ground and planting, please refer to ENH02,
Sprigging is less expensive than sodding, but it takes longer for the lawn to establish. Sprigs contain nodes on stolons, which are planted end-to-end in furrows 6–12 inches apart. Stolons should be covered with soil, but leaf blades should be exposed. The soil should be tamped and thoroughly saturated. Soil needs to be kept moist until shoots and roots begin to grow.
A number of St. Augustine grass cultivars are available commercially in garden centers as plugs. Sod also can be made into plugs by cutting it into small squares. Spacing of plugs varies from 6 to 24 inches. The closer spacing provides coverage more quickly and reduces weed intrusion. Plugs are placed in holes of the same size or in open furrows and tamped into place. A thorough watering completes the installation. The turf should then be cared for like a sprigged lawn.
Proper lawn maintenance practices are the best means for avoiding pest or stress problems and for maintaining a healthy lawn. St. Augustine grass requires inputs of fertilizer to maintain good cover and healthy growth characteristics. During certain times of the year, it generally requires supplemental irrigation. Pesticides may be needed periodically, but their use can be minimized if other cultural practices (mowing, irrigation, fertilization) are done correctly and if Integrated Pest Management (IPM) practices are followed.
Proper fertilization is very important for sustaining a healthy lawn. Fertilization and other cultural practices influence the overall health and quality of the lawn and reduce its vulnerability to numerous stresses, including weeds, insects, and disease. It is very important that anyone fertilizing their lawn be familiar with and follow the Florida-Friendly Landscaping™ Best Management Practices (FFL BMPs). These practices are designed to maintain healthy lawns and reduce any potential nonpoint source pollution of water resources that might result from lawn and landscape fertilization and other cultural practices. There are now state and, in some cities and counties, local regulations that cover lawn fertilization. Be sure to be aware of these regulations and always follow the directions on the fertilizer bag. For more information on BMPs, please refer to ENH979,
A soil test should be done prior to planting or when purchasing a home with an existing lawn to determine what nutrients are available to the lawn and what the soil pH is. The local Extension office has instructions and supplies for taking soil samples and submitting them to the Extension Soil Testing Laboratory for analysis. In particular, phosphorus levels are best determined by soil testing. Since some Florida soils are high in phosphorus, it may not always be necessary to add phosphorus to a lawn once it is established.
Florida Rule (5E-1.003) mandates that fertilizer application rates cannot exceed 1 pound of nitrogen per 1000 square feet for any application. Based on the percentage of nitrogen that is in a slowly available or slow-release form in a fertilizer, UF recommendations call for applying up to 1 pound of nitrogen per 1000 square feet of turf grass.
As a general rule, the first fertilizer application of the year should be early April in central Florida and mid-April in north Florida. In south Florida, fertilizer applications may be made throughout the year since growth is year-round. University of Florida guidelines for lawn grass fertilization offer a range of fertilizer rates over which a particular species may be successfully maintained in the various regions of the state. These ranges account for the effect that localized microclimates can have on turf grass growth. A range of rates allows for these environmental variations. An example of this would be a typical home lawn that is partially shaded and partially sunny. The grass growing in the shade needs less fertilizer than that growing in full sun. Fertilization also is affected by soil type, organic matter in soils, and practices such as clipping management. Additionally, a newly sodded lawn on a sandy soil with little organic matter requires more fertilizer than a lawn that has been fertilized for years. In Florida, new homes and new developments may be next to much older developed landscapes, and a one-size-fits-all approach to fertilization is not reasonable. These guidelines provide a base range from which the end user can begin a fertilization program. The homeowner is encouraged to initiate a program based on these guidelines and to adjust it over time based on how the turf grass responds.
The fertilizer guidelines divide the state into three geographical locations as indicated in Table 2. All rates are in pounds of nitrogen per 1000 square feet per year.
Depending on geographical location, fertilizer should be applied to St. Augustine grass in 2–6 applications from spring green-up through fall (or year-round in south Florida). Do not apply too early in the growing season, particularly in north Florida, because late-season frosts may damage the grass and the root system will not be fully grown in at this time to assimilate the nutrients. Likewise, do not fertilize too late in the year after growth has subsided.
On high-pH (>7.0) soils or where high-pH water is applied, yellow leaf blades may be an indication of iron or manganese deficiency. Application of soluble or chelated sources of these micronutrients can provide a green-up in these cases.
Note that iron is not a substitute for nitrogen, which provides the building blocks for turf grass growth and is required for turf health. While both iron and nitrogen deficiencies result in turf grass yellowing, they are distinctly different deficiencies in plants. Applying iron does not cure yellowing due to nitrogen deficiency and iron fertilizer is not a substitute for nitrogen fertilizer. Foliar iron fertilizers, such as iron sulfate or chelated iron solutions, help alleviate iron deficiencies, and nitrogen fertilizers applied according to UF/IFAS guidelines alleviate nitrogen deficiencies.
Proper mowing practices are necessary to keep any lawn healthy and attractive. Standard St. Augustine grass cultivars ('Bitter Blue', 'Classic', 'Floratam', etc.) should be maintained at a height of 3.5–4 inches. Repeatedly mowing at lower heights increases the stress on 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 . Maintaining the right height helps the grass develop a deep root system and gives a better appearance to the turf. No more than 1/3 of the leaf blades should be removed with any mowing. If possible, mowing height should be increased during periods of moisture stress or if the grass is growing in shade. Dwarf varieties have a lower growth habit and should be mowed at 2–2.5 inches for optimum health. Mowing too infrequently or too high and over-watering and over-fertilizing can cause a thatch buildup.