St. Augustine grass demands targeted post-emergent weed control that protects its delicate roots while eliminating common intruders like crabgrass, clover, and chickweed. The following selections below are among the most popular, professional-grade options available to American homeowners and lawn care professionals. Each product is designed to combat weeds in St. Augustine grass and neighboring warm-season varieties, offering post-emergent action, selectivity, and ease of use. Read on to compare ingredients, modes of action, and application considerations to help you choose the right product for your lawn.
Summary of Selected Products
| Product | Brand | Key Benefit | Approximate Coverage (per unit) |
|---|---|---|---|
| Southern Ag 006130 Atrazine St. Augustine Weed Killer | Southern Ag | Broad weed suppression in St. Augustine and centipede grass | 3,720 sq ft per quart |
| Prime Source Celsius WG | Prime Source | Fast-acting, easy mix packet for professional-grade control | Varies by mix |
| The Andersons Barricade Professional-Grade Granular Pre-Emergent | The Andersons | Pre-emergent barrier to prevent weeds | Up to 5,800 sq ft per bag |
| Liquid Harvest Mesotrione | Liquid Harvest | Post- and pre-emergent flexibility for broadleaf and grassy weeds | Depends on dilution |
| Syngenta Tenacity Herbicide | Syngenta | Broad-spectrum pre- and post-emergent weed control | 8 oz bottle fits standard applications |
Southern Ag Atrazine St. Augustine Weed Killer 32oz
Product overview and application notes emphasize practical weed suppression in St. Augustine and centipede grasses. The 32-ounce size covers a broad area, with an emphasis on controlling a range of common lawn weeds without excessive turf stress. While this ATRAZINE-based product is widely used, it’s important to follow label directions for timing, dilution, and safety to protect both turf and nearby plants. This option is well-suited for homeowners seeking an affordable, ready-to-apply solution for established warm-season lawns.
Prime Source Celsius WG – Easy Mix Post-Emerge Weed Control
Prime Source Celsius WG offers a modern, easy-mix packet approach that reduces measuring and mixing time, providing a professional-grade option for post-emergent weed control. Marketed as fast-acting with golf-course quality standards, Celsius WG targets a broad spectrum of lawn weeds while aiming to minimize turf stress. This makes it an attractive choice for homeowners who want efficient, reliable results with consistent dilution and improved handling convenience.
The Andersons Barricade Granular Pre-Emergent Weed Control
The Barricade product from The Andersons is a granular pre-emergent designed to prevent a wide range of grasses and broadleaf weeds, including crabgrass and poa annua. Its patented DG Technology ensures rapid dissolution after watering, moving the active ingredient into the soil for prolonged protection. While primarily a pre-emergent, Barricade is an essential tool in a preventative weed management plan for St. Augustine lawns, helping to reduce the reliance on post-emergent applications during peak weed seasons.
Southern Ag Atrazine St. Augustine Grass Weed Killer, 1 Gallon
This one-gallon option from Southern Ag provides an economical, broad-spectrum approach to weed suppression in St. Augustine and related grasses. Atrazine-based formulations are known for their effectiveness against a variety of broadleaf weeds and for maintaining turf health when used as directed. Users should thoroughly read the label for compatible turf types and potential regional restrictions or cautions to ensure effective results without turf damage.
Hi-Yield Atrazine Weed Killer
Hi-Yield Atrazine is positioned for use on St. Augustine and Centipede grasses, with a stated 4.00% atrazine concentration. It targets a range of annual weeds and is often used for preventive and early-season control, depending on local guidelines. As with all herbicides, application timing, turf type compatibility, and environmental conditions influence effectiveness, so adherence to the label is essential for maintaining healthy lawns.
Liquid Harvest Mesotrione – 8oz
Mesotrione-based products such as Liquid Harvest offer versatile post- and pre-emergent weed control for a variety of turfgrasses, including St. Augustine. The label notes immediate absorption with a typical full weed death window of 2–3 weeks, depending on rainfall and irrigation. This flexibility supports broader weed management plans, especially in transitional seasons when weed pressure shifts. Users should adjust watering after application to ensure the product activates properly.
Syngenta Tenacity Herbicide
Tenacity is a widely used, broad-spectrum pre- and post-emergent herbicide with the active ingredient mesotrione. It is designed to control a diverse set of weeds, including crabgrass, clover, dandelion, and ground ivy, while allowing seed or overseedings to proceed in some cases. Tenacity’s strong track record makes it a go-to option for lawn care professionals and homeowners looking for a versatile weed control tool that can be applied throughout different phases of turf growth, subject to label guidelines.
Atticus Torocity Herbicide (8oz) – Mesotrione Concentrate
Torocity by Atticus mirrors the action of leading mesotrione products, offering flexibility with pre- and post-emerge activity. It targets a broad spectrum of weeds and supports control in newly seeded areas as well as established lawns. The formulation emphasizes a wider application window, enabling more forgiving timing for homeowners managing weed pressure across growing seasons. As with all mesotrione products, careful adherence to label limits and turf compatibility remains essential for success.
Buying Guide: Key Purchase Considerations For St. Augustine Lawns
- Weed spectrum and turf compatibility: Choose products labeled for St. Augustine and centipede grasses and that target the specific weeds you see in your yard (crabgrass, clover, chickweed, goosegrass, etc.).
- Mode of action and resistance management: Rotate chemicals with different active ingredients (mesotrione, atrazine, prodiamine-based pre-emergents) to minimize resistance development and maintain long-term effectiveness.
- Timing and seasonality: Pre-emergents are most effective before weed germination, while post-emergents target existing weeds. Some products offer both pre- and post-emergent activity; plan based on current weed pressure and growth stage.
- Application method and convenience: Consider easy-mix packets, granular formulations, and ready-to-use liquids. Convenience can significantly impact adherence and results for DIY lawn care.
- Turf stress and environmental conditions: Higher temperatures and drought conditions can increase turf sensitivity. Follow label rates and avoid applications during extreme heat or water stress to protect turf health.
- Watering and activation: Some products require post-application watering to activate efficacy. Plan irrigation accordingly to maximize weed kill without washing away the product.
- Regulatory and safety considerations: Verify local regulations and ensure safe storage and handling, especially for concentrated formulations and products with restricted use in certain areas.
- Long-term lawn health: Use a combination of pre-emergent and post-emergent strategies to maintain a healthy stand of St. Augustine grass while reducing weed competition.
When selecting a post-emergent herbicide for St. Augustine grass, weigh the weed types present, your preferred application method, and seasonal timing. The products listed above provide a spectrum of options, from fast-acting liquid formulas to granular pre-emergents and versatile mesotrione-based solutions. Always follow the product label for proper dilution, application timing, and safety guidance to achieve optimal results while maintaining turf health.