Best Pre-Emergent Weed Control for St Augustine Grass Lawns 2025
Maintaining a healthy St Augustine grass lawn requires effective weed prevention, especially using a pre-emergent herbicide. This guide explores some of the best pre-emergent weed control products designed to protect your lawn from unwanted crabgrass and broadleaf weeds before they even germinate. The products reviewed below offer different formulations, application methods, and active ingredients suitable for St Augustine lawns, ensuring you find the right solution for your lawn care needs.
| Product Name | Brand | Coverage | Primary Features |
|---|---|---|---|
| Southern Ag 006130 Atrazine St. Augustine Weed Killer 32oz | Southern Ag | 3,720 sq ft per quart | Controls weeds in St Augustine and Centipede grasses |
| Southern Ag Atrazine St. Augustine Grass Weed Killer, 1 Gallon | Southern Ag | Large lawn areas (gallon size) | Kills many broadleaf weeds; suppresses crabgrass |
| The Andersons Barricade Professional Granular Pre-Emergent | The Andersons | Up to 5,800 sq ft (18 lb) | Professional-grade prodiamine, controls grassy and broadleaf weeds |
| Prodiamine 65 WDG 5lbs Pre-emergent Grass Broadleaf Weeds | Quali-Pro | Varies | Controls numerous grassy and broadleaf weeds in turf and ornamentals |
| Scotts Halts Crabgrass & Grassy Weed Preventer, 20.12 lbs | Scotts | 10,000 sq ft | Prevents germination of crabgrass and other grassy weeds |
Southern Ag 006130 Atrazine St. Augustine Weed Killer 32oz
Southern Ag’s Atrazine formula delivers targeted pre-emergent weed control specifically designed for St Augustine and Centipede grasses. One quart of this herbicide treats up to 3,720 square feet, making it a practical option for medium-sized lawns. This specialty herbicide is effective in controlling a range of broadleaf weeds that commonly threaten the health of St Augustine grass. The product is available in a 32-ounce container, weighing about 1.021 kilograms. It is a selective herbicide, meaning it won’t harm your turfgrass when applied as directed. Ideal for homeowners seeking a chemical solution that focuses on St Augustine and Centipede lawns.
Southern Ag Atrazine St. Augustine Grass Weed Killer, 1 Gallon
This gallon-sized Atrazine herbicide from Southern Ag offers broadleaf weed control and also suppresses crabgrass, making it a versatile choice for larger St Augustine grass lawns. It is suitable for use not only on St Augustine but centipede grass as well, expanding its usability for varied turf. Users can apply the liquid formula easily across their lawn, benefiting from wide coverage and effective weed management. This product is particularly useful for homeowners needing a reliable pre-emergent solution to prevent common lawn weed infestations over larger areas.
The Andersons Barricade Granular Pre-Emergent Weed Control
The Andersons Barricade is a professional-grade granular pre-emergent containing 0.48% prodiamine, ideal for early spring and fall applications. Designed specifically to prevent the germination of weed seeds, this product controls both grassy weeds like crabgrass and broadleaf weeds such as henbit and goosegrass. It covers up to 5,800 square feet per 18-pound bag, making it suitable for medium to large lawn areas. As a pre-emergent, it does not eliminate existing weeds but effectively blocks new weed growth, enhancing lawn health and appearance over time.
Prodiamine 65 WDG 5lbs Pre-Emergent for Grass and Broadleaf Weeds
Quali-Pro’s Prodiamine 65 WDG is a granular pre-emergent herbicide effective against a wide range of grassy and broadleaf weeds including crabgrass, foxtails, goosegrass, chickweed, and more. This product works well in established turfgrass, ornamentals, and perennials, offering versatile application beyond just lawns. The active ingredient is known for long-lasting residual control, and the 5-pound size provides coverage suitable for various property sizes. This product is primarily for preventative use and will not act on existing weeds, making it a vital step in seasonal lawn care routines.
Scotts Halts Crabgrass & Grassy Weed Preventer, 20.12 lbs
Scotts Halts Crabgrass & Grassy Weed Preventer is a popular granular pre-emergent designed for early spring application to prevent crabgrass and a variety of other grassy weeds. It protects up to 10,000 sq ft, providing extensive coverage with one application. Formulated to withstand rain, snow, and freezing temperatures after application, it offers reliable performance for diverse climates. Scotts Halts is effective against several lawn weeds including foxtail, spurge, barnyardgrass, and moss (except in California), plus fall weeds like Poa annua and chickweed. This product ensures season-long prevention starting from early spring.
Buying Guide for Pre-Emergent Weed Control on St Augustine Grass
Choosing the right pre-emergent for your St Augustine lawn involves several important factors to consider for optimal weed prevention and turf health.
Active Ingredient and Target Weeds
Understanding the active ingredients such as atrazine and prodiamine is crucial. Atrazine is effective specifically on St Augustine lawns against broadleaf weeds and some grassy weeds. Prodiamine offers broad control for both grassy and broadleaf weeds, including crabgrass. Consider the weed species common in your lawn area to select a product that targets your specific weed problems.
Application Timing and Frequency
Timing the application is key to a successful pre-emergent program. Most products require application before weed seeds germinate, typically in early spring and sometimes in fall for winter weed prevention. Follow the label guidance on the best timing and reapplication frequency to avoid gaps that allow weed establishment.
Coverage Area and Product Form
Matching product size to your lawn’s size avoids waste and ensures adequate coverage. Granular products like The Andersons and Scotts are easy to spread over large areas, while liquid formulations such as Southern Ag’s Atrazine offer precise control for targeted spots or medium lawns.
Lawn Grass Compatibility
Confirm that the pre-emergent is labeled safe for St Augustine grass. Some herbicides formulated for other grasses may damage this variety. Products designed specifically for St Augustine or centipede are preferable.
Prevention vs. Post-Emergent Control
Pre-emergents prevent weed seed germination but do not eliminate existing weeds. For lawns already infested, supplemental post-emergent herbicide treatments may be necessary. Some products, like Syngenta Tenacity (not reviewed here), can offer both pre- and post-emergent control for comprehensive management.
Environmental and Safety Considerations
Evaluate the environmental impact and safety instructions for each herbicide, including runoff risk and effects on pets or children. Always adhere to the manufacturer’s usage guidelines for safe, effective application.