The warm-season St. Augustine grass demands targeted weed control that protects turf while removing common lawn intruders. The following selections are designed to be effective on broadleaf and some grassy weeds while noting compatibility with St. Augustinegrass. Each option includes practical use notes, coverage, and safety considerations to help you compare products for a healthy, weed-free lawn.
Summary of selected products for St. Augustine areas
| Product | Brand | Form | Key Benefit | Coverage (approx.) |
|---|---|---|---|---|
| Atrazine St. Augustine Weed Killer 32oz | Southern Ag | Weed Killer / Liquid | Targets St. Augustine and Centipede grasses | Treats up to ~3,720 sq ft per quart |
| Atrazine Weed Killer 32 oz | Hi-Yield | Liquid Concentrate | Selective broadleaf weed control | Treats up to ~3,720 sq ft |
| WeedClear Weed Killer for Lawns Concentrate | Ortho | Liquid Concentrate | Kills dandelion, clover, and more; root level | Depends on label directions |
| WeedClear Weed Killer for Lawns with Trigger Sprayer | Ortho | Liquid Concentrate (sprayer) | Fast-acting with one application; turf-safe | Depends on label directions |
| WeedClear Weed Killer for Lawns Refill | Ortho | Liquid Concentrate | Kills 250+ weeds; targeted lawn use | Depends on label directions |
Southern Ag Atrazine St. Augustine Weed Killer
Southern Ag’s Atrazine formulation is designed specifically for St. Augustine and Centipede grasses, helping manage broadleaf and some grassy weeds. The product is shipped as a liquid concentrate and can cover a substantial lawn area when applied according to label directions. Use caution to avoid runoff into ornamental beds and consider reapplication timing to maintain control without stressing turf. One quart typically covers large areas, making it practical for mid-size lawns.
Hi-Yield Atrazine Weed Killer
Hi-Yield’s Atrazine Weed Killer is labeled for use on St. Augustine and Centipede grasses and is formulated to control a range of common weeds such as henbit, clover, and chickweed. As a concentrated liquid, it offers coverage that aligns with typical lawn sizes, achieving effective weed suppression with aesearch-based application plan. Always follow the label for the exact weed list and safety instructions to protect your turf and nearby plants.
Ortho WeedClear Weed Killer for Lawns Concentrate
Ortho WeedClear for Lawns Concentrate targets more than 250 listed weeds, including dandelion and clover, while designed to spare established lawns when used as directed. It is suitable for St. Augustinegrass (not Floratam) among other turfgrasses, with a focus on root-level kill and fast-acting results. Use as directed for spot treatment or broader applications, following the label to avoid stressing sensitive lawn types.
Ortho WeedClear Weed Killer for Lawns Refill
This refill version supports the same core weed-killing capacity as the concentrate, with a focus on eliminating dandelion, clover, and other common lawn weeds. It’s suitable for St. Augustinegrass (not Floratam) when applied according to the label. The refill option can be a cost-effective way to maintain ongoing control in larger yard spaces, provided you mix and apply precisely as instructed to ensure turf safety.
Ortho WeedClear Weed Killer for Lawns with Trigger Sprayer
This Ortho spray-ready option offers a trigger-sprayer convenience while targeting more than 250 listed weeds. It provides rapid action with a single application and claims effective results in turfgrasses, including St. Augustinegrass (not Floratam). Consider the sprayer’s nozzle pattern and coverage area to ensure even distribution and to limit over-application in sensitive zones, such as near flowerbeds or hot sunny spots that stress turf.
Liquid Harvest Mesotrione Weed Killer
Liquid Harvest Mesotrione offers a different mode of action, with immediate absorption and weed-killing activity that may take 2-3 weeks for full effect. It targets a broad spectrum of broadleaf species and grasses, including St. Augustinegrass (sod only). It requires activation by water and careful timing to maximize control, especially for pre- and post-emergent needs. Follow label directions to preserve lawn health during use.
Roundup for Lawns ₂ Concentrate
Roundup For Lawns₂ Concentrate is a robust option for Northern grasses, with an emphasis on root-level weed elimination and extended weed control. It lists a broad weeds list and offers several months of control when used as directed. While versatile, ensure it is appropriate for your St. Augustine variety and follow label notes on compatible grass types to minimize turf damage and avoid sensitive zones.
Buying Guide: Key Purchase Considerations and Comparisons
When selecting a weed killer for St. Augustine lawns, consider these factors to balance efficacy, safety, and turf health:
- Turf compatibility: Look for labels that specify St. Augustinegrass and note any cautions for Floratam varieties or other St. Augustine cultivars. Some products are not suitable for Floratam or require spot treatment.
- Weed spectrum: Identify the common weeds in your yard (dandelion, clover, crabgrass, henbit, chickweed, etc.) and choose a product that targets those species. Some formulations offer broader control, while others focus on select broadleaf weeds.
- Active ingredient and mode of action: Atrazine-based products provide tissue-selective control but require careful handling and timing. Mesotrione and other active ingredients offer different turf safety profiles; rotation can help prevent resistance and protect lawn health.
- Application form and convenience: Liquid concentrates, ready-to-use sprays, and refills each have practical considerations. Sprayer formats reduce handling but require proper nozzle settings and coverage planning.
- Coverage and timing: Estimate your lawn size to select a product with appropriate coverage per bottle or per quart. Apply during favorable weather—cool, non-windy days with adequate soil moisture or rainfall after application as directed by label.
- Environmental and safety notes: Avoid applying near desirable ornamentals, vegetables, or streams. Follow PPE guidelines and storage recommendations on every product label.
- Reapplication and management plan: Some weeds may require follow-up treatments. Consider integrating with cultural practices such as proper mowing height, irrigation management, and nutrient balance to sustain weed resistance control.
- Cost efficiency: Compare per-square-foot cost based on coverage claims and bottle size, but prioritize turf safety and weed-targeting accuracy over upfront price.
In summary, these products provide a spectrum of options designed to protect St. Augustine turf while addressing common lawn weeds. Always read labels for specific grass compatibility, application directions, and safety cautions to ensure the best results for your lawn ecosystem.