St. Augustine lawns face stubborn crabgrass invasions, especially during warm seasons. The right post-emergent option targets crabgrass and similar grassy weeds without harming your turf. This guide highlights five effective products that work well on St. Augustine grass, focusing on post-emergent action, fast results, and practical care tips. Each choice is evaluated for safety, application ease, and residual effects to help you make an informed decision for a lush, weed-free lawn.
| Product | Brand | Post/Emergent | Key Benefit |
|---|---|---|---|
| Southern Ag Atrazine St. Augustine Weed Killer | Southern Ag | Post-emergent | Controls weeds in St. Augustine and centipede grasses; covers large areas |
| BASF Drive XLR8 Crabgrass Killer | BASF | Post-emergent | Fast-acting, broad weed control with up to 30 days residual |
| Liquid Harvest Mesotrione | Liquid Harvest | Pre & Post-emergent | Versatile target range; works on dormant and active weeds |
| Agrisel Sulfentrazone 4F Weed Killer | Agrisel | Pre & Post-emergent | Broad-spectrum weed control with flexible usage |
| Hi Yield 16 Oz Grass Killer | Hi-Yield | Post-emergent | Kills grass growth selectively; safe around some non-targets |
Southern Ag Atrazine St. Augustine Weed Killer
The Southern Ag Atrazine product is designed to treat large areas with a focus on St. Augustine and centipede grasses. Each quart covers approximately 3,720 sq ft, providing post-emergent control of common lawn weeds. The formulation aims for effective weed suppression while minimizing turf injury when applied according to label directions. Users should monitor for any turf sensitivity and adjust application timing to align with weed growth stages for best results.
BASF Drive XLR8 Crabgrass Killer
BASF Drive XLR8 is a post-emergent weed killer featuring quinclorac as the active ingredient. It offers fast visible results, with up to 30 days of residual control and a rainfast time of less than an hour. The formulation targets a broad spectrum of weeds, including common crabgrass, foxtail, and various broadleaf weeds, making it a versatile option for protecting St. Augustine lawns from ongoing weed pressure.
Liquid Harvest Mesotrione
Mesotrione provides a versatile approach for lawn weed control, acting as both a pre-emergent and post-emergent option. It targets a broad range of broadleaf weeds and grasses, including crabgrass, making it suitable for St. Augustine turf. The product requires water activation for full effect, and users should ensure adequate rainfall or irrigation within 10 days of application to maximize weed death. It is compatible with several warm-season and cool-season lawn species when used as directed on the label.
Agrisel Sulfentrazone 4F Weed Killer
Agrisel Sulfentrazone 4F offers pre-emergent and post-emergent weed control with broad-spectrum efficacy. The product is designed to target crabgrass and other common lawn weeds with an emphasis on economical usage and versatile application across residential and larger spaces. It includes protective gloves for handling and application, supporting safer use when applying to active turf areas.
Hi Yield 16 Oz Grass Killer
Hi Yield Grass Killer is a selective post-emergent option designed to stop grass growth after contact. It can be used around vegetables, trees, shrubs, and ornamentals with careful attention to label directions. The product provides a targeted solution to control aggressive weed grasses while aiming to minimize collateral damage to desirable turf, making it useful for spot treatments on St. Augustine lawns.
Buying Guide: Key Purchase Considerations
- Post-emergent efficacy: Look for active ingredients proven to kill crabgrass and related weeds without excessive damage to St. Augustine grass. Quinclorac, sulfentrazone, and mesotrione are common options with wide weed coverage.
- Target weeds: Confirm that the product lists crabgrass as a primary target and that it addresses other common lawn weeds in your area to reduce multiple applications.
- Turf compatibility: Ensure the product is labeled for St. Augustine or Centipede grasses. Check tolerance notes for your specific lawn type to minimize injury risk.
- Weather and timing: Post-emergent products often work best when weeds are actively growing. Follow label guidance on temperature, precipitation, and wait times after application.
- Residual effects: Consider how long the product remains effective and whether additional applications are needed for season-long control. Some products offer up to 30 days residual control.
- Application method: Some formulas are concentrates; others are ready-to-use. Choose based on your space, ease of mixing, and sprayer compatibility.
- Safety and handling: Use gloves and follow label safety instructions. Consider bundled products that include protective gear when available.
- Environmental considerations: Prefer products with targeted action to minimize non-target plant impact and runoff concerns in areas near water sources or gardens.
- Cost and coverage: Compare coverage per bottle or per quart; larger yards may benefit from concentrates with higher coverage efficiency.
For best results, select a post-emergent option that aligns with your lawn’s grass type and weed profile. Always read and follow the official label directions, including application rates, timing, and safety precautions.