Finding herbicides that effectively target weeds in St. Augustine grass without harming the turf can be challenging. The following selected products are commonly used by homeowners and landscapers to manage broadleaf and grassy weeds while considering compatibility with St. Augustine varieties. This guide highlights five trusted options, including herbicides with Atrazine and selective weed killers, plus a weed-and-feed approach, to help you choose what fits your lawn care plan.
| Product | Brand | Type |
|---|---|---|
| Southern Ag 006130 Atrazine St. Augustine Weed Killer 32oz | Southern Ag | Atrazine weed killer |
| Southern Ag Atrazine St. Augustine Grass Weed Killer, 1 Gallon | Southern Ag | Atrazine weed killer |
| Fertilome (13917) St. Augustine Weed & Feed 15-0-4 | Ferti-Lome | Weed & feed |
| Southern Ag 006130 Atrazine St. Augustine Weed Killer 32oz & Surfactant | Southern Ag | Atrazine weed killer bundle |
| Gordon’s Ornamec 170 Grass Herbicide | Gordon’s | Selective grass herbicide |
The table above highlights five choices that are frequently used for St. Augustine lawns. Each product has its own application method, coverage area, and weed targets. Review the details in each section below to identify which option aligns with your lawn’s needs and maintenance routine.
Southern Ag 006130 Atrazine St. Augustine Weed Killer 32oz
This product targets broadleaf weeds in St. Augustine and Centipede grasses with atrazine as the active ingredient. It is designed to be applied at labeled rates that cover up to several thousand square feet per container, depending on the spray volume. Ideal for homeowners needing a straightforward application to suppress common weeds such as crabgrass and other broadleaf species. The 32-ounce bottle is a standard size for moderate lawn areas, and its compatibility with St. Augustine varieties makes it a commonly recommended option by lawn care pros.
Southern Ag Atrazine St. Augustine Grass Weed Killer, 1 Gallon
This gallon-size atrazine formula is designed for St. Augustine lawns and can also be used in centipede grass. It provides suppression of crabgrass and broadleaf weeds while targeting grassy and some broadleaf species. The larger volume reduces the frequency of refills for bigger lawns. Follow label directions for proper application timing and avoid applying during stress periods (such as extreme heat or drought) to minimize turf injury and maximize weed control results.
Fertilome St. Augustine Weed & Feed 15-0-4
This product blends pre-emergent and post-emergent weed control with a 15-0-4 fertilizer mix. It’s designed for Centipede, Zoysia, and St. Augustine lawn types, providing weed suppression while delivering essential nutrients. It is important to avoid using on Bermuda or other Northern grasses where compatibility is limited. The combined approach helps manage seasonal weed pressure while promoting turf vigor, but always follow the product’s application window and avoid over-fertilization, which can stress the lawn.
Southern Ag Atrazine St. Augustine Weed Killer (1 Gallon) with Surfactant
This package adds a non-ionic surfactant to the Atrazine weed killer, boosting spray coverage and penetration for more effective weed control in St. Augustine and centipede lawns. The surfactant helps the herbicide spread across leaf surfaces and stick to weeds, improving results on tough-to-control broadleaf and some grassy species. As with atrazine products, apply under appropriate weather conditions and avoid applying to stressed turf to minimize potential injury.
Gordon’s Ornamec 170 Grass Herbicide
Ornamec 170 is a selective grass herbicide containing fluazifop-p-butyl for controlling perennial and annual grassy weeds around ornamental plants, groundcovers, shrubs, and landscape beds. It is designed to be mixed with water and applied at specified rates (for example, 10 oz per gallon of water) for targeted weed suppression without harming many ornamentals when used as directed. This product is commonly used to reduce grassy weed competition in mixed landscape areas adjacent to St. Augustine lawns, but apply carefully to avoid drift onto desirable turf and plants.
Buying Guide: Key Purchase Considerations
When selecting a herbicide for St. Augustine grass, consider the following factors to balance efficacy, safety, and lawn health.
- Weed targets and turf compatibility: Identify whether the weeds are broadleaf or grassy and ensure the product is labeled for St. Augustine or similar warm-season grasses (Centipede, Zoysia) to minimize turf damage.
- Aerial drift and adjacent plants: For herbicides used near ornamentals or garden beds, choose products with minimal drift risk or apply during calm conditions. Surfactants can improve coverage but may increase risks if drift occurs.
- Active ingredient impact: Atrazine-based products are effective for many common lawn weeds but may have restrictions in certain regions and weather conditions. Ensure you follow local regulations and label instructions.
- Application timing: Pre-emergent options help prevent weed emergence, while post-emergent products target existing weeds. Weather and turf stress influence when to apply.
- Weed resistance and rotation: Rotating among products with different modes of action can help reduce weed resistance over time. Avoid using the same herbicide repeatedly in the same lawn season.
- Bundled products vs. stand-alone: Bundles (herbicide plus surfactant) can streamline applications, but verify compatibility and required mixing ratios for your sprayer.
- Safety and storage: Keep products out of reach of children and pets. Store in a cool, dry place, away from direct sunlight and heat sources to maintain efficacy.
Before applying any product, read and follow the label instructions for coverage area, mixing, application timing, and environmental considerations. For larger lawns, you may need a spreader or sprayer compatible with the product’s label, while smaller yards can typically use hand pump sprayers. Always wear appropriate protective gear during handling and application.