Finding an effective crabgrass killer that works well with St Augustine grass requires understanding how different herbicides interact with this warm-season turf. The products below are selected for compatibility with St Augustine, their ability to suppress or kill crabgrass and common grassy weeds, and their ease of use. This guide compares actives, coverage, and application notes to help you choose the right option for your lawn care routine.
| Product | Brand | Active/Key Feature | Size | Coverage Notes |
|---|---|---|---|---|
| Southern Ag 006130 Atrazine St. Augustine Weed Killer | Southern Ag | Atrazine; targets weeds in St. Augustine and centipede | 32 oz | Treats up to 3,720 sq ft |
| Southern Ag Atrazine St. Augustine Grass Weed Killer | Southern Ag | Atrazine; broadleaf weed control | 1 gallon | Suppression of crabgrass |
| Roundup for Lawns Crabgrass Destroyer2 | Roundup | Glyphosate-based; kills crabgrass and grassy weeds | 64 oz | Fast root kill; safe on many lawn grasses when used as directed |
| Ortho WeedClear Lawn Weed Killer Ready-To-Spray | Ortho | Crabgrass, dandelion, clover; ready-to-spray | 32 oz | Kills listed weeds down to the root |
| BASF Drive XLR8 Crabgrass Killer for Lawn & Turf | BASF | Quinclorac; post-emergent broadleaf and grassy weeds | 64 oz | Up to 30 days residual; rainfast quickly |
Note: Always follow label directions for your specific lawn type and climate. The products listed are chosen for effectiveness against crabgrass while being mindful of St Augustine grass health. Consider your lawn’s size, target weeds, and whether you prefer liquid concentrates or ready-to-use formulations when making a choice.
Southern Ag 006130 Atrazine St. Augustine Weed Killer
Product highlights: This herbicide is designed to control broadleaf weeds and grasses in St. Augustine and centipede lawns. It is shipped as a quart that treats about 3,720 square feet, making it suitable for mid- to large-sized lawns. The formula targets crabgrass among other weeds and is marketed for compatibility with St. Augustine turf. Application requires careful adherence to label directions and consideration of surrounding plants.
Southern Ag Atrazine St. Augustine Grass Weed Killer
Product highlights: This atrazine-based product is geared toward St. Augustine lawns and also applicable to centipede grasses. It provides weed suppression including crabgrass, and is offered in a 1-gallon container. Users should apply according to label instructions and avoid non-target plant exposure. It’s useful for season-long weed management when integrated into a broader lawn care plan.
Roundup for Lawns Crabgrass Destroyer2
Product highlights: This ready-to-use formula is designed to kill crabgrass and other grassy weeds to the root. It is formulated for use on Kentucky bluegrass, fine fescue, perennial ryegrass, and tall fescue. While primarily compatible with cool-season grasses, it remains a widely used option for broad weed control in lawns. Follow label directions carefully for best results and avoid applying to stressed or newly seeded lawns.
Fertilome (13915) St. Augustine Weed & Feed 15-0-4
Product highlights: This product combines pre-emergent and post-emergent weed control with a 15-0-4 fertilizer mix. It targets Centipede, Zoysia, and St. Augustine lawns, and is not recommended for Bermuda or some Northern grasses. It can help reduce crabgrass pressure while feeding the lawn, making it a dual-purpose option for warm-season lawns when used as directed.
BASF Drive XLR8 Crabgrass Killer for Lawn & Turf
Product highlights: This post-emergent herbicide uses Quinclorac to target crabgrass and a broad range of weeds. It offers up to 30 days of residual control and is rainfast quickly, aiding in rapid weed suppression. It is a versatile option for lawns requiring persistent weed management and is applicable to various turf types when used as directed.
Scotts Turf Builder Triple Action1
Product highlights: This three-in-one formula kills listed weeds, prevents crabgrass for up to four months, and feeds the lawn to promote a thick, green appearance. It targets weeds like dandelion, clover, and ground ivy while acting as a preventive measure against crabgrass and other grassy weeds, making it a convenient option for ongoing lawn care cycles.
Ortho WeedClear Lawn Weed Killer Ready-To-Spray
Product highlights: Ortho WeedClear is a ready-to-spray solution for lawn weed control, including crabgrass, dandelion, and clover. It claims fast-acting results when used as directed and is designed for broadcast treatment on a range of lawn grasses. This option is user-friendly for homeowners seeking quick, convenient weed management without mixing concentrates.
Buying Guide
The right crabgrass killer for St Augustine grass hinges on compatibility with warm-season turf and the specific weed pressures you face. Consider these key purchase factors:
- Active ingredient and mode of action: Atrazine-based products can be effective for St Augustine but have usage restrictions in some regions. Quinclorac provides post-emergent control, with residual effects up to about a month. Glyphosate-based products kill existing weeds but may affect nearby desirable grasses if misapplied.
- Formulation and ease of use: Ready-to-use sprays offer convenience for beginners, while concentrates require mixing but may be more economical per square foot. Choose based on lawn size and maintenance preference.
- Lawn compatibility: Ensure the product is labeled for St Augustine or warm-season grasses. Some products are better suited for centipede or Bermuda and may harm non-target turf.
- Coverage and application rate: Check square footage coverage per package and plan for total lawn area. Larger lawns may benefit from gallon-sized containers.
- Safety and environmental concerns: Follow label instructions, observe weather requirements, and avoid runoff into ornamental beds or water sources. Consider non-chemical lawn care methods as a supplement, like proper mowing height and overseeding when appropriate.
- Resistance management: Rotate products with different active ingredients to minimize weed resistance. Apply according to label timing to suppress crabgrass effectively without stressing St Augustine.
When selecting a product, balance the immediate need to suppress crabgrass with long-term lawn health. For homeowners seeking quick action, a post-emergent solution like Drive XLR8 or Ortho WeedClear can provide rapid results. For preventive care and lawn feeding, products like Scotts Turf Builder Triple Action1 combine weed control with fertilization, though you should not rely on them as the sole crabgrass management strategy. Always tailor your approach to your specific climate, soil type, and lawn age for best results.