Best Post Emergent Herbicide for St Augustine Grass to Control Weeds Effectively 2025
Maintaining a pristine St. Augustine grass lawn requires effective weed control, especially with the right post emergent herbicide. We’ve selected top herbicides designed specifically for St. Augustine grass, balancing weed control effectiveness with grass safety. Below is a quick comparison of the best products to help you make an informed choice for your lawn care needs.
| Product | Brand | Target Weeds | Application Type | Size |
|---|---|---|---|---|
| Southern Ag 006130 Atrazine St. Augustine Weed Killer | Southern Ag | Broadleaf weeds in St. Augustine and Centipede grass | Post emergent | 32oz |
| Syngenta Tenacity Herbicide | Syngenta | 46 Broadleaf and grass weeds including crabgrass, dandelion | Pre and post emergent | 8oz Liquid |
| Prime Source Celsius WG | Guoml | Post emergent broadleaf and grassy weeds | Post emergent (easy mix packet) | 0.226 oz packet |
| Hi-Yield Atrazine Weed Killer | VPG | Broader weeds including annual bluegrass and chickweed | Post emergent | Concentrate size varies |
| BASF Drive XLR8 Crabgrass Killer | BASF | Crabgrass, foxtail, broadleaf weeds like clover and dandelion | Post emergent | 64oz concentrate |
Southern Ag 006130 Atrazine St. Augustine Weed Killer 32oz
This atriazine-based herbicide is formulated specifically for St. Augustine and Centipede grasses. It controls a wide range of broadleaf weeds effectively while being safe for the grass with proper application. A 32oz container treats up to 3,720 square feet, making it suitable for medium-size lawns. The product is light tan in color and easy to handle. The concentration and efficacy provide good value for controlling unwanted weeds without damaging the lawn.
Syngenta Tenacity Herbicide – Pre and Post Emergent Control
Tenacity from Syngenta is a liquid herbicide with a broad-spectrum action, targeting 46 weed species including crabgrass, dandelion, and clover. Its active ingredient is mesotrione, derived naturally. Unique to this product is its dual pre- and post-emergent use, making it valuable for seeding and overseeding as well. It selectively controls weeds without harming St. Augustine grass, offering flexibility in application timing. Its precise targeting and environmentally friendly profile make it an effective option for homeowners.
Prime Source Celsius WG – Easy Mix Post Emergent Weed Control
Prime Source Celsius WG offers a professional-grade post emergent herbicide in an easy-to-use packet, eliminating the need for measuring. Its formula provides fast-acting weed control designed for various turfgrasses, including St. Augustine. This granular packet ensures convenience and accuracy in mixing, leading to efficient application and dependable weed suppression. Ideal for homeowners who want a user-friendly product with effective results.
Hi-Yield Atrazine Weed Killer Suitable for St. Augustine Grass
Hi-Yield Atrazine Weed Killer contains 4% atrazine aimed at controlling a variety of weeds such as annual bluegrass, chickweed, and mouseear. This product is recommended for St. Augustine and Centipede grasses, providing efficient post emergent control. Widely utilized in lawn care, it targets broadleaf and grassy weeds effectively while preserving the health of the turf. Proper application ensures long-lasting weed suppression and healthier grass growth.
BASF Drive XLR8 Crabgrass Killer – Post Emergent Broadleaf and Grass Control
BASF Drive XLR8 is a concentrated herbicide featuring quinclorac as its active ingredient. It delivers up to 30 days of residual control and rapidly absorbs into plants through its water-based formulation, targeting troublesome grassy weeds like crabgrass, foxtail, and torpedo grass as well as key broadleaf weeds such as clover and dandelion. Rainfast in under an hour, it reduces the need for repeated applications and protects your St. Augustine grass effectively.
Buying Guide for Post Emergent Herbicides on St. Augustine Grass
Choosing the right post emergent herbicide for St. Augustine grass requires careful consideration of several factors to ensure both effective weed control and grass safety.
1. Target Weed Spectrum
Analyze what types of weeds are most problematic in your lawn. Herbicides like Syngenta Tenacity cover a broad weed spectrum including grassy and broadleaf weeds, while others like atrazine-based products focus more on broadleaf types commonly found in St. Augustine lawns.
2. Safety for St. Augustine Grass
Not all herbicides are safe for St. Augustine grass. Products with ingredients such as atrazine or mesotrione are specifically labeled for use on St. Augustine, minimizing the risk of lawn damage. Avoid herbicides that do not explicitly state compatibility with this grass type.
3. Application Method and Convenience
Consider how much effort and expertise the product requires. Granular packets like Prime Source Celsius WG simplify mixing and measuring, while concentrates may require precise dilution. Choose based on your comfort level and convenience.
4. Residual Control and Reapplication Frequency
Longer residual activity reduces the need for repeated applications. BASF Drive XLR8 offers residual control lasting around 30 days, helping to maintain a weed-free lawn longer.
5. Additional Lawn Benefits
Some products, such as the Fertilome Weed & Feed, combine herbicide action with fertilization, providing nourishment alongside weed control. This may be advantageous for overall lawn health but requires careful attention to grass species compatibility.
6. Environmental Considerations
Look for products with formulations that minimize environmental impact. Some herbicides use naturally derived active ingredients or have reduced runoff potential. Always follow label instructions to protect your lawn and surrounding ecosystem.
In summary, the best post emergent herbicide for St. Augustine grass will depend on your specific weed problems, lawn size, and application preferences. Prioritize complete compatibility and safety to maintain a lush, green lawn free from invasive weeds.