Crabgrass can rapidly invade St Augustine lawns, especially during warm seasons. This article spotlights effective post-emergent crabgrass killers that work well on St Augustine grass, offering options from trusted brands and focusing on performance, safety, and ease of use. The products highlighted below target crabgrass and other common lawn weeds while supporting turf health.
| Product | Brand | Active Focus | Notes |
|---|---|---|---|
| Drive XLR8 | BASF | Crabgrass and other weeds | Post-emergent, fast-acting with up to 30 days residual |
| Southern Ag Atrazine St. Augustine Weed Killer | Southern Ag | Weeds in St. Augustine and centipede grasses | Post-emergent with broad weed control |
| Liquid Harvest Mesotrione 8oz | Liquid Harvest | Broadleaf and grassy weeds; post and pre-emergent potential | versatile; visible results with time |
| Agrisel Sulfentrazone 4F | Agrisel | Pre- and post-emergent broad-spectrum weed control | Includes protective gloves; versatile use |
| Hi Yield 16 Oz Grass Killer | Hi-Yield | Post-emergent grass weed control | Targeted grass-killer with garden-appropriate safety |
Note: Always follow label directions for timing, application, and turf compatibility. While all options target crabgrass, formulation differences influence performance on St Augustine grass and climate conditions.
Drive XLR8 Crabgrass Killer
- Brand: BASF
- Active ingredients include quinclorac for rapid weed uptake
- Water-based formulation for faster absorption and improved performance
- Extended residual control up to 30 days
- Rainfast in less than an hour
Drive XLR8 is designed for post-emergent control of crabgrass and a broad spectrum of lawn weeds. It emphasizes quick uptake, effective turf protection, and a residue that helps suppress new weed growth between applications. Ideal for lawns needing rapid weed suppression with minimal downtime.
Southern Ag Atrazine St. Augustine Weed Killer
- Brand: Southern Ag
- Treats up to 3,720 sq ft per quart
- Controls weeds in St. Augustine and centipede grasses
- Light tan formulation for even coverage
Atrazine-based weed killers are commonly used for stubborn broadleaf and grassy weeds in St. Augustine turf. This option emphasizes coverage and compatibility with St. Augustine and centipede lawns, helping reduce weed pressure while maintaining turf integrity when applied as directed.
Liquid Harvest Mesotrione 8oz
- Brand: Liquid Harvest
- Active ingredient: Mesotrione
- Targets 46 broadleaf species and grasses, including crabgrass
- Suitable for various cool-season and warm-season grasses; sod-friendly
Mesotrione-based products offer post- and pre-emergent capability with a broad weed target spectrum. They permit flexible timing in lawns where crabgrass and other broadleaf weeds compete with established St Augustine turf. Application requires moisture for activation; follow label rainfall guidance for best results.
Agrisel Sulfentrazone 4F
- Brand: Agrisel
- Pre-emergent and post-emergent broad-spectrum weed control
- Stops 100+ weeds, including crabgrass
- Pet-safe formulation and includes protective gloves in the package
Agrisel Sulfentrazone 4F combines pre- and post-emergent action, giving turf managers flexibility to target germinating seeds and existing weeds. It is marketed as pet-safe when used as directed, with an emphasis on broad-spectrum control that supports healthy St Augustine lawns by reducing weed competition.
Hi Yield Grass Killer
- Brand: Hi-Yield
- Selective post-emergent herbicide for grasses
- Targets weed grasses while minimizing damage to desirable lawn species
- Fast-acting growth suppression within days
Hi Yield Grass Killer provides targeted post-emergent control for unwanted grass weeds. It is designed to be compatible with various lawn types, including St Augustine, and aims to minimize collateral damage to desirable turf when used according to label directions. It is particularly useful when crabgrass or similar grasses invade established turf.
Buying Guide: Key Purchase Considerations for St Augustine Lawns
- Weed stage and product timing: Post-emergent products work on existing weeds, while pre-emergents prevent germination. For crabgrass, a combination approach may be needed—post-emergent for current weeds and pre-emergent for upcoming seasons.
- Active ingredients and turf compatibility: Quinclorac, mesotrione, sulfentrazone, and atrazine have different weed spectrums and turf tolerances. Confirm compatibility with St Augustine grass to avoid turf injury and ensure effective control.
- Mode of action and rotation: Use products with diverse modes of action to minimize weed resistance. Rotate active ingredients across seasons when possible.
- Residual control and rainfall requirements: Some products offer extended residual protection, while others rely on rainfall to activate. Plan applications around weather and irrigation to maximize uptake.
- Application timing and safety: Early-season applications often yield better control, especially for pre-emergent products. Follow label directions for mowing restrictions, pet and family safety, and wind or drift precautions.
- Lawn health and overseeding considerations: Strong, healthy St Augustine lawns tolerate herbicide use better. Avoid applying during drought or heat stress, and consider overseeding or aeration if weed pressure is persistent.
- Coverage and cost efficiency: Evaluate spray coverage per quart or bottle and how many square feet you can treat. For larger lawns, products with higher coverage efficiency may reduce the number of applications needed.
- Environmental and safety considerations: Some formulations include gloves or pet-safety guidance. Follow disposal guidelines and store products safely away from children and pets.
- Targeted versus broad-spectrum control: If you have a lawn mixed with ornamentals or nearby beds, choose a selective product that minimizes risk to desired plants.