A lush Saint Augustine lawn that chokes out weeds and stays green through the southern summer heat is the goal — but the wrong cultivar or a mismatched fertilizer plan can leave you with thatchy patches, invasive Bermuda, or stunted growth. The market is flooded with generic grass products that simply don’t work for this specific warm-season turf, so knowing exactly what your lawn needs is the difference between curb appeal and constant frustration.
I’m Mohammad Maruf — the founder and writer behind Gardening Beyond. I’ve spent hours dissecting the technical specs, owner reports, and regional performance data for each product in this guide to ensure you get a recommendation that actually matches your Saint Augustine lawn’s biology.
Whether you’re filling bare spots, suppressing dollarweed, or establishing a new lawn from plugs, finding the right product starts here. The following analysis will help you identify the best saint augustine grass solutions for your specific growing conditions and maintenance goals.
How To Choose The Right Saint Augustine Grass Product
Saint Augustine grass is a warm-season turf that spreads via above-ground stolons and is almost never grown from seed in a home lawn — you will be choosing between live plugs, granular weed-and-feed fertilizers with specific NPK ratios, and liquid herbicides containing atrazine. The wrong choice wastes a season of growth and invites weed pressure.
Choose Live Plugs for Establishing or Expanding a Lawn
If you are starting a new St. Augustine lawn from scratch or filling large bare areas, plugs are the only reliable method. Unlike fescue or Bermuda, St. Augustine does not come true from seed — you must use vegetative plugs or sod. Look for a semi-dwarf cultivar like Palmetto, which offers a finer texture and better shade tolerance than the coarse Floratam, and verify that the plugs arrive with visible green tissue and a healthy root system. A 2×2 inch plug planted on 12-inch centers can fill a 100-square-foot area within a single active growing season.
Select a Weed & Feed with Atrazine for Established Lawns
For an existing St. Augustine lawn that has weed pressure from dandelion, clover, or dollarweed, a granular product with atrazine as the active herbicide is the standard. Atrazine is one of the few chemicals that kills emerged broadleaf weeds without severely damaging St. Augustine turf — but it must not be used on Bermuda or Northern grass types. A ratio of 15-0-4 (nitrogen-phosphorus-potassium) provides the nitrogen St. Augustine needs for green-up during spring without adding phosphorus, which is already abundant in many southern soils. Coverage is typically measured per 2,500 to 5,000 square feet, so measure your lawn before buying.
Use a Liquid Atrazine Spray for Spot Treatment and Suppression
When weeds are concentrated in specific areas or you need to target crabgrass suppression alongside broadleaf control, a liquid concentrate like Southern Ag Atrazine offers precise control. A one-gallon jug mixes to cover roughly 500 square feet and can be applied with a pump sprayer. The trade-off is slower visible results — expect two to four weeks for full weed death — and the need to reapply every two to three weeks for persistent weeds like dollarweed. Always verify your sprayer is clean and calibrated to avoid over-application that can temporarily yellow the turf.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| Fertilome 15-0-4 Weed & Feed | Granular Fertilizer | Established lawn feeding + pre-emergent weed control | 15-0-4 NPK; 12.8 lbs. | Amazon |
| Palmetto St. Augustine Plugs | Live Grass Plugs | New lawn establishment or bare-spot repair | 3 extra-large plugs; semi-dwarf | Amazon |
| Scotts Sun & Shade Mix | Grass Seed Blend | Overseeding Northern lawns (not St. Augustine) | 5.6 lbs.; covers 2,240 sq. ft. | Amazon |
| Scotts EZ Seed Patch & Repair | Patch Repair Mix | Spot-filling bare areas in any lawn type | 10 lbs.; mulch + seed + fertilizer | Amazon |
| Southern Ag Atrazine | Liquid Herbicide | Broadleaf weed control on established St. Augustine | Atrazine; 1 gallon | Amazon |
In‑Depth Reviews
1. Fertilome (13915) St. Augustine Weed & Feed 15-0-4
The Fertilome 15-0-4 formulation hits the exact NPK ratio that established St. Augustine lawns need during the spring green-up phase: high nitrogen to push blade density, zero phosphorus to avoid runoff issues in phosphorus-rich southern soils, and potassium for root strength. The 12.8-pound bag covers up to 5,000 square feet if you follow the broadcast rate for maintenance, and the granular format makes application straightforward with a standard rotary spreader.
Owner reports consistently note that this product both thickens the turf and suppresses emerging weeds when applied at the proper time — generally early spring as the lawn breaks dormancy. The built-in pre-emergent and post-emergent herbicide is atrazine, which targets dandelion, clover, and other broadleaf weeds while leaving St. Augustine unharmed. Users in Florida and coastal Carolina report particularly good results with St. Augustine that was recovering from drought damage.
One limitation: this product is strictly for Centipede, Zoysia, and St. Augustine lawns. Do not use it on Bermuda or any Northern cool-season grass, as the atrazine content can severely damage those turf types. The label also stresses timing — applying too late in the growing season reduces weed control effectiveness and can push excessive top growth before dormancy.
What works
- 15-0-4 ratio matches the nutrient profile St. Augustine needs in spring without excess phosphorus.
- Atrazine herbicide kills emerged broadleaf weeds and provides pre-emergent suppression.
- Covers a large area — up to 5,000 sq. ft. per bag at the maintenance rate.
What doesn’t
- Not for use on Bermuda grass or Northern grass types — check your lawn composition.
- Application timing is narrow; best results require application before soil temperatures exceed 80°F.
- Granules must be watered in within 48 hours or weed control efficacy drops.
2. Palmetto St. Augustine Grass Plugs (3 Count)
The Palmetto cultivar is a significant upgrade over the coarse Floratam variety that dominates big-box sod lots. Its leaf blade width is comparable to Bitterblue — finer and softer to the touch, without the prickly feel that Floratam develops as it matures. When mowed at the recommended 3- to 4-inch height, Palmetto can even be mistaken for fescue from a distance, giving a lush, carpet-like appearance that many southern homeowners desire.
These plugs arrive as three extra-large specimens (roughly 2×2 inches each) with visible green tissue and established root systems. The cultivar is well-documented for superior shade tolerance — it outperforms other St. Augustine varieties under tree canopies and on north-facing slopes — and it demonstrates strong drought tolerance in field tests. Multiple owners report that plugs survived unplanted for up to two weeks in the tray and still produced runners reaching six inches within a month of planting.
One important caveat: St. Augustine spreads vegetatively, so these plugs require several months of warm-season growth to fill a large area. The price per plug is slightly higher than buying in bulk from specialty suppliers, but the convenience of Prime shipping and the health guarantee from Florida Foliage make this a reliable entry point for homeowners repairing 50 to 100 square feet. Be prepared to water daily for the first two weeks and avoid letting the soil dry out during root establishment.
What works
- Palmetto semi-dwarf habit produces a plush, fine-textured lawn without excessive thatch buildup.
- Excellent shade tolerance — holds green in partial sun where Floratam thins out.
- Plugs arrive healthy with minimal yellowing and can tolerate a short delay before planting.
What doesn’t
- More expensive per plug than bulk options from specialty seed companies.
- Requires daily watering for the first two weeks to establish stolons.
- Not returnable if planted — inspect plugs immediately upon arrival.
3. Scotts EZ Seed Patch & Repair Sun and Shade (10 lbs.)
Scotts EZ Seed Patch & Repair is a three-in-one formulation that combines a high-performance grass seed blend, a mulch that expands to hold moisture, and a controlled-release fertilizer. It is designed specifically for repairing bare spots, and the included tackifier helps prevent the seed from washing away even on gentle slopes. Owners report notable germination within 7 to 10 days when daytime temperatures stay between 60°F and 80°F, making it a viable option for spot-fixing thinning areas.
This product works best as a patch tool — it is not intended for full-lawn renovation or overseeding of an entire St. Augustine lawn. The grass seed blend is a proprietary mix that contains fine fescue, perennial ryegrass, and Kentucky bluegrass for the sun-and-shade coverage, not a St. Augustine cultivar. For purely St. Augustine lawns, using this product would introduce a different grass type that may stand out in texture and color.
Several long-term users report that the initial results are impressive — thick green growth within two weeks — but the patchy areas tend to be overtaken by weeds after one to two years unless you also apply a pre-emergent weed killer. The 10-pound bag covers roughly 225 square feet, which is relatively small for the price. If you are maintaining a mixed lawn where appearance uniformity matters less, this is a convenient tool; for a pure St. Augustine monoculture, live plugs are a better long-term investment.
What works
- Germinates fast — often visible within one week under consistent watering.
- Mulch layer retains moisture and reduces seed wash-away on light slopes.
- Easy application: no separate fertilizer or peat moss needed.
What doesn’t
- Contains cool-season grass species, not St. Augustine; color and texture will differ.
- Coverage is limited — 225 sq. ft. per bag is small for the price per square foot.
- Results can be inconsistent between batches; some users report patchy germination.
4. Southern Ag Atrazine St. Augustine Weed Killer (1 Gal.)
When broadleaf weeds invade an established St. Augustine lawn, atrazine is the active ingredient most turf experts reach for — and Southern Ag’s one-gallon concentrate is a straightforward, no-frills delivery system. Atrazine works by disrupting photosynthesis in susceptible broadleaf species like dandelion, dollarweed, and chickweed while leaving St. Augustine largely unharmed. This formulation also provides suppression of crabgrass when applied as a pre-emergent, though its primary strength is post-emergent broadleaf control.
Users consistently report that it kills dollarweed without browning the turf, but note that the effect is slow — full weed death typically takes two to four weeks, and reapplication every two to three weeks is needed for persistent populations. The 1-gallon jug treats roughly 500 square feet when mixed per label instructions, which is a relatively small coverage area compared to granular products. Some owners mix it with a non-ionic surfactant (sticker-spreader) to improve adhesion on waxy weed leaves.
A significant safety concern emerged in one verified review: the product arrived without a label, safety instructions, or ingredient list. Because atrazine is a restricted-use pesticide in some states, always verify that the jug is fully labeled before applying. This product is also toxic to Bermuda grass if applied during its active growth phase — use only on St. Augustine and Centipede lawns. For homeowners already comfortable with liquid sprayers and precise mixing, this is a cost-effective way to control weeds without broadcasting fertilizer you don’t need.
What works
- Selective atrazine chemistry kills dollarweed and other broadleaf weeds without killing St. Augustine.
- Also provides suppression of crabgrass when applied early in the season.
- Economical for spot treatment; one gallon makes multiple applications.
What doesn’t
- Slow results — visible weed death takes 2 to 4 weeks.
- Labeling issues reported: some jugs arrive without instructions or safety warnings.
- Very small coverage area per gallon — only about 500 sq. ft. at the recommended rate.
5. Scotts Turf Builder Grass Seed Sun and Shade Mix (5.6 lbs.)
Scotts Turf Builder Sun and Shade Mix is a perennial ryegrass, fine fescue, and Kentucky bluegrass blend designed for cool-season lawns and transitional zones. It is not a St. Augustine product — the seed mix creates a fine-bladed, dark green turf that thrives in soil temperatures between 55°F and 70°F. The 5.6-pound bag covers up to 2,240 square feet for overseeding, making it one of the most economical grass seed options on the market per square foot.
If your lawn is a mix of St. Augustine and cool-season grasses — common in the upper transition zone like Tennessee or North Carolina — this blend can help thicken bare areas that St. Augustine struggles to fill during cooler months. The included Root-Building Nutrition (a slow-release fertilizer coating) helps germination even in moderate shade and average soil conditions. Several user reports confirm visible sprouts within 10 days with twice-daily watering.
The key limitation for St. Augustine owners is that this seed will not match the blade width, color, or growth habit of your existing St. Augustine turf. The result is a patchy, two-tone appearance. Additionally, a small number of reviews reported higher-than-expected weed content in recent batches, which is a concern if you are applying it over a weed-free area. For a pure St. Augustine lawn, this product is a mismatch; for a mixed lawn that needs quick greening in fall, it works well.
What works
- Excellent germination rate in both full sun and moderate shade conditions.
- Covers a large area for the price — up to 2,240 sq. ft. at the overseeding rate.
- Fertilizer coating supports root development during early establishment.
What doesn’t
- Contains cool-season grass types, not St. Augustine; will not match an existing St. Augustine lawn.
- Some batches reported higher weed seed content than expected.
- Slow to germinate in poor soil — may require additional topsoil or compost for best results.
Hardware & Specs Guide
NPK Ratio for St. Augustine
The nitrogen-phosphorus-potassium ratio is critical for St. Augustine because this grass is a heavy nitrogen feeder during active growth. A 15-0-4 formulation delivers 15 percent nitrogen for blade green-up and density, zero phosphorus (most southern soils already have adequate phosphorus, and adding more can cause runoff and algae blooms), and 4 percent potassium for root vigor and disease resistance. Avoid high-phosphorus ratios like 10-10-10 for established lawns unless a soil test indicates a deficiency.
Atrazine as a Selective Herbicide
Atrazine is the only active ingredient widely approved for post-emergent broadleaf weed control without injuring St. Augustine turf. It disrupts the electron transport chain in photosynthesis, killing susceptible broadleaf weeds like dollarweed, dandelion, and chickweed over two to four weeks. It also provides pre-emergent suppression of crabgrass. Atrazine is a restricted-use pesticide in some states and requires careful mixing — follow the label rate of roughly 8 to 10 ounces per gallon of water for hand sprayer application, and never use on St. Augustine that is stressed by drought or high heat.
St. Augustine Plug Cultivars: Palmetto vs. Floratam
Palmetto is a semi-dwarf cultivar with a leaf blade width similar to Bitterblue (roughly 6 to 8 mm) and a softer texture than Floratam, which has coarser, pricklier blades. Palmetto demonstrates superior shade tolerance — it maintains density with as little as four hours of direct sun daily — and it is less prone to thatch accumulation in full sun. Floratam is more aggressive in full sun but becomes leggy and thin in shade. When buying plugs, always ask for the specific cultivar name; generic “St. Augustine plugs” may contain Floratam, which will disappoint if your lawn has significant shade areas.
Granular vs. Liquid Application Methods
Granular weed-and-feed products (like the Fertilome 15-0-4) are best for broadcast application over large, uniform lawns because they combine fertilization and weed control in one pass with a spreader. Liquid atrazine concentrates are better for spot treatment of weed patches, but they require a pump sprayer and careful calibration to avoid over-application that can yellow the turf. Granules are less prone to drift on windy days, while liquids offer precision around flower beds and driveways. For most homeowners with a St. Augustine lawn between 2,500 and 5,000 square feet, a granular spring feeding plus a liquid spot treatment in summer is the optimal combination.
FAQ
Can I use Scotts EZ Seed on an existing St. Augustine lawn to fill bare spots?
How often should I apply Fertilome 15-0-4 Weed & Feed to my St. Augustine lawn?
Will atrazine from Southern Ag kill my St. Augustine lawn if I use too much?
How long does it take for Palmetto St. Augustine plugs to fill a bare area completely?
Why is there no St. Augustine grass seed available, only plugs and sod?
Final Thoughts: The Verdict
For most gardeners, the best saint augustine grass winner is the Fertilome 15-0-4 Weed & Feed because it delivers the exact 15-0-4 NPK ratio your St. Augustine lawn needs for dense green growth while simultaneously controlling broadleaf weeds with atrazine during the critical spring window. If you want a finer-textured, shade-tolerant lawn from scratch, grab the Palmetto St. Augustine Plugs. And for spot-treating dollarweed without broadcasting unnecessary fertilizer, nothing beats the Southern Ag Atrazine liquid concentrate.