Grass Types
Identifying Types of St Augustine Grass: A Cultivar Guide
When homeowners and landscapers refer to St. Augustine grass (Stenotaphrum secundatum), they are rarely talking about a single, uniform plant. Instead, they are referencing a diverse species with over a dozen distinct commercial cultivars, each engineered or selected for specific environmental tolerances, disease resistance, and visual profiles. Misidentifying your specific cultivar can lead to catastrophic lawn failure, as maintenance requirements—particularly regarding nitrogen application, mowing height, and shade tolerance—vary drastically between varieties.
The Botanical Baseline: What Defines St. Augustine?
Before differentiating between specific types of St Augustine grass, you must confirm the species itself. St. Augustine is a warm-season, stoloniferous turfgrass. Unlike Bermudagrass, which spreads via both above-ground stolons and below-ground rhizomes, St. Augustine spreads exclusively via thick, spongy above-ground stolons. The leaves exhibit folded vernation (they emerge from the sheath folded rather than rolled) and feature a distinctively truncate, boat-shaped leaf tip. The ligule—the membrane where the leaf blade meets the sheath—is characterized by a short fringe of hairs, a critical diagnostic feature that separates it from lookalikes like Centipedegrass.
Cultivar Identification Matrix: Visual & Performance Traits
The following matrix breaks down the primary commercial cultivars available in the 2026 market, highlighting the morphological and environmental data necessary for accurate identification and selection.
| Cultivar | Blade Width & Texture | Color Profile | Shade Tolerance (Min. Direct Sun) | Cold Hardiness (USDA Zones) | Primary Vulnerability |
|---|---|---|---|---|---|
| Floratam | 9-11mm (Coarse) | Medium to Light Green | 5-6 hours | 9-11 | Cold damage, Chinch bugs |
| CitraBlue | 7-9mm (Medium) | Deep Blue-Green | 4-5 hours | 8-11 | Large patch (if overwatered) |
| Palmetto | 6-8mm (Fine) | Emerald Green | 3-4 hours | 8-10 | SAD Virus, Chinch bugs |
| Seville | 5-7mm (Fine/Dwarf) | Dark Blue-Green | 3-4 hours | 9-11 | Thatch buildup, Nematodes |
| Sapphire | 6-8mm (Fine) | Dark Blue-Green | 4 hours | 8-10 | Gray leaf spot |
Deep Dive: The Major St. Augustine Cultivars
Floratam (The Industry Standard)
Released jointly by the University of Florida and Texas A&M in 1973, Floratam remains the most widely planted St. Augustine cultivar in the US Sunbelt. It was specifically selected for resistance to the St. Augustine Decline (SAD) virus and chinch bugs, though modern chinch bug biotypes have largely overcome this resistance. Identification marker: Floratam features exceptionally long internodes (the space between stolon nodes), often exceeding 4 inches in actively growing turf, giving it a somewhat open, sprawling appearance compared to newer, denser cultivars.
CitraBlue (The Modern Contender)
Developed by the Texas A&M AgriLife Extension and released commercially around 2020, CitraBlue has rapidly captured market share due to its superior disease resistance and striking color. It exhibits exceptional resistance to gray leaf spot, large patch, and take-all root rot. Identification marker: CitraBlue has a noticeably denser canopy, shorter internodes, and a distinct blue-green hue that remains vibrant even under mild drought stress. It requires roughly 20% less nitrogen than Floratam to maintain optimal color.
Palmetto & Seville (The Shade Specialists)
Palmetto (discovered in 1988) and Seville (a 1980s dwarf mutant) are the go-to cultivars for heavily shaded landscapes. Palmetto features a finer texture and shorter leaf blades, allowing it to capture filtered light more efficiently. Seville is a true dwarf cultivar with a lower growth habit, reducing mowing frequency. Failure mode warning: Both cultivars are highly susceptible to the SAD virus. If your soil history indicates previous SAD outbreaks, avoid these cultivars entirely and opt for CitraBlue or Floratam.
Expert Warning: The SAD Virus Factor
St. Augustine Decline (SAD) is a viral disease that causes yellow mottling and eventual turf death. There is no chemical cure. According to data from the University of Florida IFAS Extension, cultivars like Floratam, CitraBlue, and Raleigh possess genetic resistance to SAD, while Palmetto, Seville, and Bitterblue are highly vulnerable. Always verify your cultivar's SAD status before planting in established neighborhoods.
St. Augustine Decline (SAD) is a viral disease that causes yellow mottling and eventual turf death. There is no chemical cure. According to data from the University of Florida IFAS Extension, cultivars like Floratam, CitraBlue, and Raleigh possess genetic resistance to SAD, while Palmetto, Seville, and Bitterblue are highly vulnerable. Always verify your cultivar's SAD status before planting in established neighborhoods.
Field Identification: How to Tell Them Apart in the Turf
If you have inherited a lawn and need to identify the existing St. Augustine cultivar, rely on morphological measurements rather than color, which fluctuates with soil pH and nitrogen levels. Follow this step-by-step diagnostic framework:
- Measure the Internode Length: Part the canopy and measure the distance between the nodes on the primary stolons. If the internodes are consistently 3 to 5 inches long and the stolons are thick (over 1/4 inch in diameter), you likely have Floratam.
- Examine the Blade Width: Pick a mature, fully expanded leaf from the middle of the canopy. If the blade is narrower than 7mm and feels soft to the touch, suspect a fine-textured dwarf variety like Seville or Palmetto.
- Check the Canopy Density: Push your fingers into the thatch layer. Cultivars like CitraBlue and Sapphire produce highly dense, interlocking lateral shoots that create a spongy, resistant feel. Floratam will feel more open and allow easier penetration to the soil surface.
- Observe the Winter Dormancy Pattern: In transitional zones (Zone 8b/9a), cultivars like Raleigh and Sapphire will retain a degree of green coloration or transition to a uniform straw-brown, while Floratam suffers distinct, patchy cold-kill damage at temperatures below 35°F.
Purchasing & Establishment Costs (2026 Market Rates)
Understanding the financial commitment of different cultivars is vital for budgeting. St. Augustine is almost exclusively established via sod or plugs; seed is not commercially viable for these specific vegetative cultivars. Below are the average wholesale-to-retail pallet prices (covering 450 square feet) as of early 2026:
- Floratam: $200 – $260 per pallet ($0.45 – $0.58 per sq. ft.). Widely available at big-box retailers and local sod farms.
- CitraBlue: $340 – $420 per pallet ($0.75 – $0.93 per sq. ft.). Premium pricing reflects its patented status and superior disease resistance.
- Palmetto: $240 – $290 per pallet ($0.53 – $0.64 per sq. ft.). Moderate premium for shade-tolerant traits.
- Seville: $280 – $330 per pallet ($0.62 – $0.73 per sq. ft.). Higher cost due to slower lateral spread rates during sod farm production.
Pro Tip for Plug Establishment:
If budget constraints prevent full sod installation, purchase flats of 2.5-inch plugs. Space CitraBlue plugs 12 inches apart in a grid pattern. Due to its aggressive lateral growth, CitraBlue will achieve full canopy closure in 10 to 14 weeks during the peak summer growing season, compared to 16 to 20 weeks for Floratam.
If budget constraints prevent full sod installation, purchase flats of 2.5-inch plugs. Space CitraBlue plugs 12 inches apart in a grid pattern. Due to its aggressive lateral growth, CitraBlue will achieve full canopy closure in 10 to 14 weeks during the peak summer growing season, compared to 16 to 20 weeks for Floratam.
Common Misidentifications & Lookalikes
Homeowners frequently confuse St. Augustine with Centipedegrass (Eremochloa ophiuroides), especially when the turf is stressed or mowed too high. While both feature broad leaves and above-ground stolons, their botanical structures differ significantly. According to the National Turfgrass Evaluation Program (NTEP), Centipedegrass exhibits strictly alternating leaf arrangement along the stolon, whereas St. Augustine leaves appear opposite or clustered at the nodes. Furthermore, Centipedegrass features a distinctly pointed leaf tip and a V-shaped collar region, completely lacking the fringe of hairs found on the St. Augustine ligule. Misapplying St. Augustine herbicides (like atrazine) to Centipedegrass can cause severe phytotoxicity, making accurate identification a matter of turf survival.
Frequently Asked Questions
Can I mix different types of St. Augustine grass in the same lawn?
While technically possible, mixing cultivars is highly discouraged. Different growth rates, blade widths, and color profiles will result in a patchy, uneven appearance. Furthermore, varying shade and water requirements will cause one cultivar to outcompete the other over a 3-to-5-year period, leading to a fragmented canopy that invites weed intrusion.
Which St. Augustine cultivar is best for coastal, salt-heavy environments?
Seville and Floratam exhibit the highest natural salt tolerance among commercial cultivars. If you are within a mile of the coast and experience frequent salt spray or utilize brackish irrigation water, Seville is the optimal choice due to its combined salt tolerance and lower mowing requirements.
Why is my CitraBlue turning yellow despite regular watering?
CitraBlue is highly efficient at nutrient uptake and requires less nitrogen than older cultivars. However, it is particularly sensitive to iron and manganese deficiencies in high-pH soils (above 7.2). If your soil test confirms high pH, apply a chelated iron supplement (Fe-EDDHA) at a rate of 2 ounces per 1,000 square feet to restore the deep blue-green coloration without triggering excessive blade growth.
