St Augustinegrass Guide

Patchy color, thin growth, and mysterious brown areas in a St. Augustine lawn usually come down to a small set of causes: shade stress, improper mowing height, watering habits, or disease and insects that exploit those stress points. The key is to match what you see with a simple field test. Check sunlight hours with your phone clock over a day, use a screwdriver test to gauge soil moisture and compaction, and look closely at individual blades for spots or chewing.

Once you know the stress, the fix becomes straightforward. Raise or lower the mowing height into the correct range for your variety, water deeply but infrequently so soil is moist 4-6 inches down, and correct shade issues or swap to a more shade-tolerant cultivar. If you see distinct lesions or insects, spot-treat with the correct fungicide or insecticide for St. Augustinegrass, and avoid blanket treatments "just because," since those often mask the real problem instead of solving it.

Healthy St. Augustine responds fairly quickly if the underlying issue is addressed. Color often improves in 7-14 days after dialing in water and mowing, while stolons can re-knit thin areas over 4-8 weeks during peak growing season. Keeping notes on what you change and when you see improvements will help you fine-tune a stable, repeatable care routine for your yard.

Understanding St. Augustinegrass Basics

What Is St. Augustinegrass?

St. Augustinegrass (Stenotaphrum secundatum) is a warm-season turfgrass widely used in the coastal and southern United States. Botanically, it is a coarse-textured grass with broad, flat blades and prominent stolons (above-ground runners) that creep over the soil surface. Those stolons root at the nodes and allow the grass to form a dense, carpet-like mat.

Because it is a warm-season species, St. Augustinegrass grows most aggressively when daytime temperatures are roughly 80-95°F and soil temperatures stay above about 65°F. In winter, especially when temperatures drop into the 40s, it slows down, may turn brown or tan, and goes semi-dormant. Unlike cool-season grasses, it does not tolerate prolonged freezing well, which is why it is concentrated in Gulf Coast, Atlantic coastal, and deep southern regions.

Pros and Cons of St. Augustinegrass Lawns

St. Augustinegrass offers a set of strengths that make it a top choice in warm, humid, and coastal regions, but it also has clear limitations. Understanding both sides will help you decide if this grass is appropriate for your site and maintenance style.

On the benefit side, St. Augustine has better shade tolerance than most warm-season turfgrasses. While it prefers full sun, many cultivars can maintain acceptable density with 4-6 hours of direct sun or filtered light, which is useful under open tree canopies. Its coarse blades and thick stolon network create a lush, cushioned surface that looks like a green carpet when managed properly. It also has relatively good salt tolerance, so it performs better than many other species in coastal yards exposed to sea spray or saline irrigation water. The aggressive stolons help it cover bare soil quickly when established from sod or plugs and help it recover from minor damage.

The tradeoffs are equally important. St. Augustinegrass is not as cold-hardy as zoysiagrass or tall fescue. In marginal climates or during unusually cold winters, it can suffer winterkill, especially in low or poorly drained spots. It is also susceptible to several key pests and diseases, especially chinch bugs, gray leaf spot, and large patch (also called brown patch). St. Augustine tolerates routine foot traffic but is not ideal for high-wear sports or dog runs; repeated abrasion can thin stolons and expose soil. Finally, it is rarely established from seed. Sodding, plugging, or sprigging are the primary methods, which affects both cost and renovation strategies.

Ideal Climate and Growing Zones

St. Augustinegrass is best suited to the warm, humid coastal plain, including much of Florida, the Gulf Coast states, coastal Texas, and the southern Atlantic seaboard. It can also grow inland where winters are mild. As a rough guide, it performs reliably in USDA hardiness zones 8-11 and can be marginal in protected areas of zone 7b, depending on cultivar and microclimate.

From a temperature standpoint, active growth is strongest when daytime highs are 80-95°F and nighttime lows remain above about 60°F. When extended periods of temperatures drop below 50°F, the grass slows dramatically and may discolor. Repeated hard freezes or single-digit temperatures can kill turf, especially less cold-tolerant cultivars such as Floratam in fringe regions.

Sunlight requirements depend on the specific cultivar, but as a general rule, standard St. Augustinegrass performs best in full sun with at least 6-8 hours of direct light. Shade-tolerant types can maintain a usable lawn with 4-6 hours of sun or bright dappled shade, but sustained heavy shade (less than 3-4 hours of direct light) typically leads to thinning, elongated leaves, and bare soil under trees. Even though St. Augustine is more shade-tolerant than bermudagrass, there is still a threshold where turf is not a realistic expectation.

Soil and Site Requirements

St. Augustinegrass is adaptable to a range of soil textures, from sandy coastal soils to heavier loams, which is part of why it is so widely used in Florida and Gulf states. It performs well in well-drained sandy or sandy loam soils and can handle lower organic matter better than some cool-season grasses. However, extremely compacted clays and poorly drained sites tend to be problematic because shallow roots and extended wetness create ideal conditions for disease.

The preferred soil pH range for St. Augustinegrass is roughly 6.0-7.5. It will tolerate slightly acidic or slightly alkaline soils outside this window, but significant deviations, such as pH below 5.5 or above 8.0, often lead to nutrient availability problems and poor performance. A soil test is the best way to know where you stand and whether lime or sulfur adjustments are appropriate.

Drainage is a critical, often overlooked factor. If water stands in low areas for more than 24 hours after a 1 inch rainfall, or if your screwdriver test shows saturated soil at 2-3 inches depth for days at a time, disease pressure increases significantly. Simple homeowner checks include observing puddling patterns, checking downspout discharges, and probing the soil after irrigation. Where drainage is consistently poor, grading, French drains, or soil amendment during renovation may be necessary before St. Augustinegrass can truly thrive.

Choosing the Right St. Augustinegrass Variety

Overview of Popular St. Augustinegrass Cultivars

Not all St. Augustinegrass is the same. Over the past several decades, breeders have released multiple cultivars with different strengths in shade tolerance, cold tolerance, disease resistance, and texture. Picking the correct variety is one of the highest leverage decisions you can make because it locks in certain capabilities and limitations for the life of the lawn.

In practical terms, your options often depend on what local sod farms produce. Common choices include Floratam, Palmetto, Raleigh, Seville, Delmar, and regional or branded types. Broadly, Floratam is vigorous and sun-loving, Palmetto and Seville lean toward better shade and finer texture, and Raleigh offers improved cold tolerance for the northern edge of the St. Augustine range.

Classic vs. Improved Cultivars

Many older lawns are planted with what is often called "common" or standard St. Augustinegrass. These traditional types have relatively coarse leaves, good vigor, and basic shade tolerance, but they lack the specific improvements bred into newer cultivars. They typically require mowing at the higher end of the range, around 3-4 inches, to maintain density and cannot tolerate very low mowing heights.

Improved cultivars have been selected for traits such as better shade performance, finer leaf texture, greater disease resistance, or adaptability to closer mowing. For example, some semi-dwarf types can be maintained around 2-2.5 inches with a sharp rotary or reel mower, which gives a more manicured appearance but also increases maintenance sensitivity. Improved cultivars often show better resistance to certain diseases, but there is rarely a "disease-proof" grass. Instead, they tend to be more forgiving under stress when combined with correct cultural practices.

Cultivar Profiles

Floratam. Floratam is one of the most widely used St. Augustine cultivars in Florida and parts of the Gulf Coast. It has large, coarse leaves, vigorous stolon growth, and strong drought tolerance once established. However, this vigor is optimized in full sun. In moderate to heavy shade, Floratam tends to thin quickly, which makes it a poor choice under trees or on the north side of structures. It generally performs best at a mowing height around 3.5-4 inches.

Palmetto. Palmetto is marketed as a semi-dwarf, shade-tolerant St. Augustinegrass. It has a somewhat finer texture and can maintain reasonable density with less light than Floratam, commonly in the 4-6 hour direct sun range, especially if trees are limbed up to allow scattered light. Many homeowners appreciate its softer feel and slightly shorter mowing potential, roughly 2.5-3 inches, though it still benefits from not being scalped.

Raleigh. Raleigh is a cold-tolerant cultivar often recommended for the upper South and parts of the transition zone where winter lows are more severe. It has medium-coarse texture and moderate shade tolerance. Raleigh can still suffer winter damage in extreme cold events, but it tends to outperform Floratam in marginal climates. It is somewhat sensitive to certain diseases, so fertilization and watering require attention.

Seville, Delmar, and similar types. Seville and Delmar are examples of dwarf or semi-dwarf St. Augustine cultivars with finer leaf blades and a lower growth habit. They can produce a dense, attractive turf at lower mowing heights, near 2-2.5 inches, assuming the mower is sharp and height is consistent. However, their lower growth habit also means they can accumulate thatch more quickly and may be less forgiving of irregular mowing or scalping. Shade performance varies, but many homeowners use them in mixed sun and filtered shade sites for a more manicured appearance.

How to Choose the Best Variety for Your Yard

Matching the cultivar to your yard begins with objective observations rather than brand names. Start by mapping the sun and shade pattern. Over one clear day, record where and when direct sun hits key lawn sections and how many total hours each area receives. This information will immediately rule out full-sun cultivars in heavily shaded zones.

Next, consider winter temperatures and local disease and insect history. If you live near the northern limit of St. Augustinegrass, prioritize cold-tolerant options like Raleigh over Floratam. In hot, humid coastal zones with high gray leaf spot pressure, seek cultivars known locally to handle that disease better, and be prepared to adjust nitrogen rates accordingly.

An actionable checklist for selection is:

• At least 6-8 hours of sun in most areas: full-sun cultivars like Floratam or vigorous standards can perform well.
• Only 4-6 hours of sun or significant tree shade: favor shade-tolerant types like Palmetto or certain dwarf varieties.
• Frequent hard freezes in winter: choose a more cold-hardy cultivar such as Raleigh where available.
• Preference for a low, manicured look: consider semi-dwarf or dwarf cultivars and be ready for more precise mowing and thatch monitoring.

Finally, confirm availability with local sod suppliers and ask what performs best in your immediate region. Local experience from sod farms and extension publications often captures nuances that general guides cannot, such as how a specific cultivar handles a common regional fungus or soil salinity level.

Establishing St. Augustinegrass: Sod, Plugs, and Sprigs

Site Preparation

Successful St. Augustinegrass lawns start with thorough site preparation. Before any sod or plugs arrive, clear existing vegetation with a non-selective herbicide or by physically removing old turf and roots. Leaving living competitors in place often leads to mixed, patchy lawns that are difficult to manage. After vegetation is removed, grade the soil to eliminate low spots, promote surface drainage away from structures, and ensure a smooth, even surface.

A soil test should be completed several weeks before planting. Use the results to adjust pH with lime or sulfur if needed and to address severe nutrient deficiencies. Aim to incorporate amendments into the top 4-6 inches of soil. This is easier before sod is installed than later, and it directly affects root development depth and drought resilience.

Sod vs. Plugs vs. Sprigs

St. Augustinegrass is most commonly established by sod or plugs. Sod gives an instant lawn appearance and full coverage but has the highest upfront cost. Plugs are small pieces of sod, typically 2-4 inches square, that are planted on a grid and allowed to grow together over time. Sprigs are stolon pieces without attached soil, used more in large-scale or professional installations.

Sod is the best choice when you need immediate erosion control, want an instant finished look, or are renovating a highly visible front yard. Plugs are more economical for large areas or patient homeowners who can accept several months of fill-in time during peak growing season. Plug spacing usually ranges from 12-18 inches on center; at 12 inches with good care, full coverage can occur in 8-12 weeks during ideal warm weather. Sprigging is rarely used for small residential lawns due to handling complexity but can be effective in rural or large-acreage settings.

Planting Timeline and Early Care

The optimal establishment window for St. Augustinegrass is when soil temperatures are consistently above 65°F and there are at least 8-10 weeks of warm weather remaining before first frost. In much of the South, this means late spring through mid-summer. Planting too early in cool soils or too late heading into fall often results in weak rooting and higher winter injury risk.

Immediately after laying sod, roll it with a water-filled roller to ensure good soil contact, then irrigate thoroughly. The goal is to wet the sod and the top 3-4 inches of underlying soil. For the first 10-14 days, water lightly but frequently to keep the sod layer and top inch of soil consistently moist, without creating standing water. As you see new growth and resistance when gently tugging on the sod, gradually transition to deeper, less frequent irrigation to encourage roots to chase moisture downward.

For plugs, keep the planting holes and surrounding soil moist, not just the plug itself. New stolons will begin to spread across bare soil over the first month if temperatures and moisture are favorable. Delay the first mowing until the grass reaches about one-third higher than your target height, then cut with a sharp blade and remove no more than one-third of the leaf blade in a single mow.

Mowing St. Augustinegrass Correctly

Recommended Mowing Heights

Mowing height is one of the most powerful control levers you have for St. Augustinegrass health. For standard cultivars, target a height between 3 and 4 inches. For semi-dwarf types like Palmetto or Seville, 2.5-3 inches is typical, while some dwarf cultivars can be kept near 2-2.5 inches with careful management.

The "one-third rule" applies: never remove more than one-third of the leaf blade at a single mowing. If your lawn has grown too long, raise the mower, cut it down in two or three steps over a couple of weeks, and then resume your normal target height. Scalping St. Augustinegrass, especially in heat, quickly leads to stress, weed invasion, and disease susceptibility.

Mowing Frequency and Blade Care

In peak growth periods, you may need to mow every 5-7 days to maintain the correct height. In slower growth phases, such as early spring or fall, a 10-14 day interval can be adequate. The specific schedule should follow growth rate rather than the calendar. Grass that is regularly cut at the correct height will have denser tillering, better root development, and improved weed resistance.

Sharp mower blades are essential. Dull blades tear the wide leaves of St. Augustinegrass, leaving frayed, brown tips that make the lawn look dry and unhealthy even when it is well-watered. In warm, sandy regions where blades pick up grit, sharpening several times per season is often justified. You can confirm blade sharpness by inspecting the cut tips of a handful of clippings: clean, straight edges indicate a sharp blade; shredded, fibrous ends indicate it is time to sharpen.

Watering St. Augustinegrass

How Much and How Often

Deep, infrequent irrigation produces the healthiest St. Augustinegrass root systems. As a baseline, most established lawns perform best with about 1-1.5 inches of water per week during active growth, including rainfall. In sandy soils with low water holding capacity, this often means irrigating 2-3 times per week with each event providing roughly 0.5 inches. In heavier soils, fewer but deeper irrigations may be appropriate.

To calibrate your system, place several straight-sided containers (like tuna cans) in the irrigated area and run your sprinklers to see how long it takes to apply 0.5 or 1 inch of water. This simple test converts "15 minutes per zone" guesses into specific, measurable output. Then adjust run times so that the total weekly amount aligns with the 1-1.5 inch target, increasing slightly during extreme heat or drought as needed.

Timing and Drought Stress Signs

Water most of the lawn's weekly requirement in the early morning, between about 4 a.m. and 9 a.m. This timing reduces evaporation, allows foliage to dry as the sun rises, and minimizes disease pressure. Avoid regular evening irrigation, because prolonged leaf wetness overnight favors fungal diseases like gray leaf spot and large patch.

Signs that your St. Augustinegrass needs water include a dull blue-green color, folded or rolled leaves, and footprints or mower tracks that remain visible for several minutes instead of springing back. If you see these indicators in the afternoon and the soil 3-4 inches down feels dry when probed, schedule irrigation that night or early the next morning. Chronic underwatering results in thinning and weed invasion, while chronic overwatering, especially on poorly drained sites, leads to shallow roots and disease.

Fertilizing St. Augustinegrass

Fertilizer Needs and Timing

St. Augustinegrass responds significantly to nitrogen (N) but also requires phosphorus (P) and potassium (K) in balanced amounts based on soil test results. In many warm climates, total annual nitrogen needs fall in the 2-4 pounds of N per 1,000 square feet range, split into multiple applications during the growing season. The exact rate depends on growth expectations, soil type, and cultivar.

A common schedule is to apply 0.5-1.0 pound of nitrogen per 1,000 square feet in late spring after full green-up, followed by one or two similar applications spaced 6-8 weeks apart in summer. Avoid fertilizing too early, while grass is still partially dormant, or too late, within 6-8 weeks of expected first frost, because this can encourage succulent growth that is more prone to winter injury and disease.

Product Selection and Application

Select fertilizers with an appropriate N-P-K ratio for your soil test and local regulations. In many established lawns with adequate phosphorus, a product with a high first number and low or zero middle number is typical, such as 15-0-15 or 16-4-8, depending on soil K levels. Including some slow-release nitrogen, such as 30-50 percent of total N, helps provide steady feeding and reduces surge growth and leaching losses in sandy soils.

Calibrate your spreader according to the product label, and apply in overlapping passes to achieve uniform coverage. After application, water lightly to move granules off the leaves and into the thatch and soil, unless the product instructions specify otherwise. Avoid exceeding recommended rates, because over fertilization, particularly with nitrogen, significantly increases disease susceptibility, especially to gray leaf spot during humid summer weather.

Weed and Pest Management in St. Augustinegrass

Common Weeds and Control Strategies

Weeds in St. Augustinegrass lawns typically signal underlying issues with mowing height, fertility, or light. Thin, scalped areas are prone to invasion by crabgrass, goosegrass, spurge, and sedges. The first line of defense is consistent mowing at the correct height and maintaining a dense turf canopy. In most cases, a thick St. Augustine mat will outcompete many annual weeds.

Preemergent herbicides applied in early spring, when soil temperatures approach 55°F for several days, can prevent annual grassy weeds like crabgrass from establishing. However, you must confirm that any product you choose is labeled as safe for St. Augustinegrass, because this species is sensitive to certain active ingredients that are tolerated by other warm-season grasses. For existing broadleaf weeds, selective postemergent herbicides designed for St. Augustine can be used as spot treatments. Always follow label directions closely, especially regarding temperature limits and stress conditions, to avoid turf injury.

Insect Pests and Diagnosis

Chinch bugs are one of the most serious insect pests of St. Augustinegrass. They feed in hot, dry, sunny areas and cause irregular patches of yellowing and browning that can resemble drought stress. If you suspect chinch bugs, focus on areas near sidewalks, driveways, and south-facing slopes. To confirm, part the grass near the border between healthy and declining turf and look in the thatch layer for small, fast-moving insects with black and white markings. A common threshold is roughly 15-20 chinch bugs per square foot before treatment is recommended, but local recommendations may vary.

Other potential pests include sod webworms and armyworms. These caterpillars chew on leaves and produce notched or ragged damage, often accompanied by moths flying up at dusk when you walk the lawn. For any suspected insect problem, confirm presence with visual inspection or a soapy water flush before applying insecticides. Treat only when pests reach damaging levels, and rotate active ingredients over seasons to slow resistance development.

Diseases in St. Augustinegrass

Gray leaf spot and large patch are two major diseases in St. Augustinegrass. Gray leaf spot typically appears in warm, humid conditions after nitrogen fertilization, causing small, gray to brown, oval lesions on leaf blades and general thinning in shaded or overwatered areas. Large patch often develops in cool, moist conditions, especially in spring and fall, creating circular or irregular patches of orange-brown turf with a yellow halo at the edges.

If you see expanding patches that are not explained by watering patterns or insect activity, examine affected leaves closely. For disease diagnosis, you can also send samples to a local plant diagnostic lab. Cultural control measures include moderating nitrogen applications, improving air movement and drainage, and adjusting irrigation timing. Fungicides labeled for St. Augustinegrass and the specific disease can be used preventively or curatively based on extension recommendations and product labels.

Renovation and Seasonal Care

Renovating Thin or Damaged Areas

St. Augustinegrass can recover from moderate damage on its own through stolon growth if underlying problems are corrected, but heavily thinned or dead patches often require active renovation. Begin by diagnosing and fixing the original cause, whether it was shade, drainage, pests, or incorrect mowing. There is little value in replanting into the same uncorrected stress environment.

Once the cause is addressed, rake away dead material and loosen the top inch of soil. For small areas, you can plug or patch with sod pieces, setting them flush with the surrounding turf and watering to keep them moist until rooted. For larger damaged zones, complete resodding during peak growing season may be more efficient. With good soil contact and moisture, new stolon growth should begin to re-knit seams within 2-4 weeks.

Seasonal Care Calendar

A simple seasonal framework helps keep St. Augustinegrass on track.

• Late winter to early spring: Clean up debris, service the mower, and wait for consistent warm-up and greening before the first light fertilizer application if soil tests indicate a need. Apply preemergent herbicides, if desired, as soil temperatures approach 55°F.
• Late spring to summer: Maintain regular mowing in the appropriate height range and irrigate to supply 1-1.5 inches of water per week. Apply main nitrogen feedings spaced about 6-8 weeks apart, monitoring for pests and diseases during hot, humid periods.
• Late summer to early fall: Gradually reduce nitrogen rates and avoid late, heavy fertilization. Address any compaction or drainage issues, and adjust irrigation downward as temperatures moderate and evapotranspiration decreases.
• Late fall to winter: As growth slows and dormancy approaches in cooler regions, cease fertilization, remove or mulch leaves, and continue mowing as needed at the normal height until growth stops. In frost-prone areas, accept seasonal discoloration as normal for a warm-season grass.

What Other Guides Miss

Many general St. Augustinegrass guides gloss over two key aspects that make the difference between a consistently healthy lawn and one that cycles through problems: confirmation tests and timing windows.

First, confirmation tests. Instead of assuming a brown patch is always drought, insect, or fungus, combine simple checks: the screwdriver test for soil moisture and compaction, a sun-hours log, and close inspection of leaf blades and thatch. If the screwdriver cannot reach 4-6 inches easily, you have compaction. If a patch stays wet for 24 hours after rain, you have a drainage problem. If pests or lesions are not visible, chemical controls should not be the first response.

Second, timing windows are often underemphasized. Establishment, major fertilization, and renovation all depend on soil temperature and the remaining length of warm season, not just the month on the calendar. Planting sod when soil is below 65°F or pushing nitrogen within 6 weeks of expected frost greatly increases winter injury risk, yet many schedules ignore this. For best results, align major actions with active growth phases and verify soil temperatures with an inexpensive thermometer or local extension soil temperature reports.

Conclusion

St. Augustinegrass can deliver a dense, comfortable, and visually appealing lawn when its specific needs are matched to your site and maintenance habits. The fundamentals are straightforward: choose a cultivar that fits your sun, shade, and climate; prepare and drain the soil properly; mow within the correct height range; water deeply but not daily; and base fertilization on soil tests and active growth periods. Most chronic problems in St. Augustine lawns trace back to stress from shade, improper mowing height, moisture extremes, or mis-timed inputs, which pests and diseases then exploit.

By using simple field tests and observing your lawn through the seasons, you can build a care routine that keeps the turf dense and resilient with fewer surprises. Ready to take the next step? Check out our guide on diagnosing brown patches in warm-season lawns for more detailed troubleshooting when specific trouble spots appear.