Best Post-Emergent Weed Killers for St. Augustine Grass
Answer: For St. Augustine lawns, select post-emergent weed killers that specifically mention safe use on St. Augustine, Bermudagrass, Centipede, or Zoysia when applicable. The top options in this guide target broadleaf and grassy weeds while minimizing damage to warm-season grasses. This article highlights five products chosen for compatibility with St. Augustine grass, ease of use, and coverage. It also notes any limitations to help you pick the right product for your lawn’s needs and climate. Buyers should consider weed types, timing (spring vs. fall), application area, and whether you need a one-season or multi-application plan. The table below summarizes key choices.
| Product | Best For | Approximate Coverage | Notes |
|---|---|---|---|
| Prime Source Celsius WG | Post-emerge weeds in warm-season lawns | Established on packet; check date | Date stamped is manufacturing date, not expiration |
| Celsius WG 2-Pack with Bug And Blade Card | Season-long weed control for warm-season lawns | Up to 4,000 sq ft per full program | Two treatments per season; safe on St. Augustine |
| Fertilome St. Augustine Weed & Feed 15-0-4 | Pre & post-emergent weed control with fertilizer | 25.6 lbs bag | Designed for St. Augustine, Centipede, Zoysia |
| Spruce Weed & Grass Killer Kit | Targeted weed and grass control around lawns | 64 oz spray bottle | Pet safe spray; reusable sprayer |
| Spectracide Weed & Grass Killer Concentrate | Broadleaf weeds and grasses in driveways/walkways | 64 oz concentrate | Use with sprayer; broad application |
Prime Source Celsius WG – Easy Mix Packet
Features: Date stamped on packaging is the Manufacturing Date, NOT an expiration date.
Best for: Homeowners needing a straightforward post-emergent weed control option in warm-season lawns, with emphasis on compatible use on commonly managed St. Augustine lawns.
Why selected: This product provides a simple mix format and is targeted at post-emergent weed control in warm-season turf. It’s included for its ease of use and specific focus on post-emergent control in St. Augustine-friendly environments.
Caution: Verify the mixing and application instructions on the package, as the manufacturing date note indicates the labeling might rely on shelf life considerations rather than a traditional expiration date. Avoid over-application to prevent lawn stress.
Celsius WG Herbicide 2-Pack with Bug And Blade Card
Features: TWO TREATMENTS, ONE SEASON — COMPLETE WEED CONTROL UP TO 4,000 SQ FT — The two-pack delivers a full spring + fall treatment cycle in one order. Includes a Weed ID Card; Triple-mode-of-action formula; Not for cool-season grasses. Safe on St. Augustine, Bermuda, Centipede, and Zoysia.
Best for: Warmer-season lawns needing a season-long treatment plan and weed resistance management, especially when post-emergent control is needed across multiple weed types.
Why selected: This option provides a structured spring and fall program with broad weed-killing mechanisms, designed to work without harming St. Augustine grass when used as directed.
Caution: Not recommended for cool-season grasses; ensure your lawn is a warm-season type and follow the two-application schedule for best results.
Fertilome St. Augustine Weed & Feed 15-0-4
Features: Pre & post-emergent weed control with 15-0-4 fertilizer; safe for St. Augustine, Centipede, Zoysia; not for Bermuda grasses or Northern grasses.
Best for: Homeowners seeking combined weed control and fertilization for St. Augustine lawns in warmer regions where centipede and zoysia are also present.
Why selected: The product blends nutrient support with weed control, simplifying lawn care where multiple warm-season grasses are in play.
Caution: Avoid using on Bermuda grasses or cool-season lawns; confirm suitability for your specific grass mix before application.
Spruce Weed & Grass Killer Kit
Features: 64 Oz sprayer with power wand; includes 2 AA batteries; pet-safe handling notes; reusable sprayer.
Best for: Lawn owners who want a ready-to-use garden sprayer system to apply post-emergent and granular-like weed killers around lawns, gardens, and flower beds.
Why selected: This kit provides a convenient, concentrated spray approach that can be tailored to spot-treat stubborn weeds around St. Augustine areas.
Caution: Use as directed around pets and children; the spray should not contact desirable turf in some scenarios—follow label directions for spraying near desirable plants.
Spectracide Weed & Grass Killer Concentrate
Features: Mix & apply with sprayer; 64 Oz concentrate; Kills broadleaf weeds and grasses to the root; visible results in 3 hours.
Best for: Home owners needing a quick-acting concentrate for driveways, walkways, and similarly treated areas adjacent to St. Augustine lawns.
Why selected: Provides a broad-spectrum option for non-turf areas nearby, complementing turf-focused post-emergent products.
Caution: Not all formulations are safe for warm-season turf; use exactly as directed near desirable grass to avoid damage.
Buying Guide: Key Purchase Considerations
- Weed scope: Identify whether you need broadleaf-only control or also grasses. Some products target broadleaf weeds, while others handle multiple weed types.
- Timing:Spring and fall applications are common; consider a two-treatment plan for season-long control in warm-season lawns.
- Lawn type compatibility: Confirm the product is safe for St. Augustine grass and any other grasses in your yard (Bermuda, Centipede, Zoysia).
- Coverage and dilution: Check square footage coverage per package and dilution ratios to estimate total costs and applications.
- Safety and handling: Review label directions, especially around pets, children, and flowering ornamentals.
- Application method: Choose between ready-to-use sprays, granules with fertilizer, or concentrates that require mixing with water and a sprayer.
Frequently Asked Questions
- What is post-emergent weed control for St. Augustine grass? Post-emergent products target weeds that have already germinated, helping reduce established weed populations after they appear.
- Can I use these products on St. Augustine while it is actively growing? Yes, but follow label directions for timing and temperatures to minimize turf stress.
- Are there products safe for both St. Augustine and Zoysia? Some formulas note safe use on both; always verify the label for your specific grass varieties.
- Should I apply in spring or fall? A two-treatment plan in both spring and fall often provides season-long control for warm-season lawns.
- What should I do if I mix too much product? Do not apply excessive concentrations; dilute as directed and consider re-treating smaller areas if needed.
- Is it better to use a fertilizer-and-weed product or separate products? A combined weed-and-feed can simplify care, but ensure compatibility with your lawn type and weed spectrum.