St. Augustine grass requires targeted weed control to maintain a healthy, lush lawn. This guide highlights effective post-emergent herbicides that work well on St. Augustine and Centipede lawns, helping you manage broadleaf and grassy weeds after they sprout. The selections below balance performance, ease of use, and suitability for Southern turf. Use the included buying guide to compare options and choose the right product for your lawn-care routine.
| Product | Brand | Active Use | Coverage | Format |
|---|---|---|---|---|
| Southern Ag 006130 Atrazine St. Augustine Weed Killer | Southern Ag | Post-emergent weed control | 3,720 sq ft per quart | 32 oz bottle |
| Prime Source Celsius WG | Prime Source | Post-emergent weed control | Golf-course quality | 0.226 oz packet |
| BioAdvanced Season Long Lawn Weed Killer + Preventer | BioAdvanced | Post-emergent with long-term prevention | Up to 4,000 sq ft | 10 lb granular |
| Southern Ag Atrazine St. Augustine Grass Weed Killer | Southern Ag | Post-emergent weed control | 1 gallon | Liquid |
| Atticus Torocity Herbicide | Atticus | Post- and pre-emergent control | Broad spectrum | 8 oz |
Note: Always read label directions for proper application schedules, compatible grasses, and safety precautions. For St. Augustine lawns, select products labeled for use with St. Augustinegrass to ensure both effectiveness and safety for your turf.
Southern Ag Atrazine St. Augustine Weed Killer 32oz
Product overview: This atrazine-based weed killer is designed to control broadleaf weeds in St. Augustine and centipede grasses. It provides broad weed suppression and can help reduce weed populations across treated areas. The package size covers substantial lawn areas, making it a practical choice for moderate to large yards. Users should follow label directions for safe and effective mixing and application, particularly around desirable turf.
Key features: One quart treats up to about 3,720 square feet; targets weeds in St. Augustine and Centipede grasses; package weight around 1.021 kilograms. This product emphasizes post-emergent activity, helping you tackle existing weed problems in warmer southern climates.
Prime Source Celsius WG – Post Emerge Weed Control
Product overview: Celsius WG is a post-emergent weed control product designed for rapid action and professional-grade results. The easy mix packet is marketed to simplify mixing and application, and it claims fast-acting weed control suitable for high-quality turf management. It’s positioned for professional-quality outcomes, which can translate to visible weed control improvements in St. Augustine lawns when used as directed.
Key features: Easy mix packet with no measuring required; professional golf-course quality results; fast-acting weed control. These attributes support straightforward, efficient weed management, especially for homeowners seeking dependable post-emergent performance.
BioAdvanced Season Long Lawn Weed Killer + Preventer
Product overview: A granular weed killer designed for southern lawns, including St. Augustine varieties, with a preventive component to deter new weed growth for up to six months. It targets a broad range of broadleaf weeds and offers crabgrass prevention, helping to maintain weed-free turf over time. The product treats up to 4,000 square feet, providing a long-term lawn care option for southern grass types.
Key features: Kills and prevents weeds for up to 6 months; crabgrass prevention; suitable for southern lawns and St. Augustinegrass; treats up to 4,000 sq ft. This option combines immediate post-emergent control with ongoing preventive benefits.
Southern Ag Atrazine St. Augustine Grass Weed Killer, 1 Gallon
Product overview: This atrazine-based herbicide targets broadleaf weeds in St. Augustine grass while offering cross-application compatibility with centipede lawns. It provides suppression for crabgrass and other common lawn invaders, depending on the weed spectrum in your area. The gallon size supports larger yard applications and repeat treatments as needed, following label directions for safe use around turf and ornamentals.
Key features: Kills many broadleaf weeds; also used in centipede grass; provides suppression of crabgrass. Its post-emergent action helps address visible weed issues, contributing to improved lawn appearance and health when applied properly.
Atticus Torocity Herbicide (8oz)
Product overview: Torocity contains 40.0% mesotrione, the same active ingredient as the leading Tenacity brand, offering broad-spectrum control for many weeds in lawns and turf. It supports flexible timing with both pre- and post-emergent activity, expanding application windows to stop new weeds and knock down existing ones. It targets crabgrass, clover, oxalis, dandelion, and other common lawn weeds.
Key features: Contains high mesotrione content; flexible pre/post-emergent timing; broad-spectrum weed control. This product provides versatility for managing weeds in St. Augustine lawns across different seasons and weed pressures.
Buying Guide
Choosing the right post-emergent herbicide for St. Augustine requires weighing weed type, lawn health, and application logistics. Consider the following factors to make an informed choice:
- Weed spectrum: Identify the weeds present in your lawn (broadleaf, grassy, or both). Some products target broadleaf weeds, while others address crabgrass and grassy invaders.
- St. Augustine compatibility: Ensure the product label explicitly lists St. Augustine or Floratam as safe for use on your grass variety. Some products are labeled for broadgrass compatibility but may not be ideal for St. Augustine.
- Mode of action: Post-emergent herbicides work differently (systemic vs. contact, selective vs. non-selective). Selectives with minimal turf injury are preferred for lawn use.
- Longevity and prevention: If you want ongoing weed control, consider products that include a preventive component or require follow-up applications for season-long protection.
- Application timing: Some products are effective on actively growing weeds, while others offer flexibility for pre- and post-emergent use. Follow timing guidelines based on weed life cycles.
- Coverage and dilution: Check the coverage rate per bottle or packet to estimate cost per square foot. Proper mixing is essential to avoid turf damage and ensure efficacy.
- Safety and environment: Read safety precautions, label warnings, and environmental impact guidance. Use protective gear as recommended and keep pets and children away during application if advised.
- Climate considerations: Southern lawns often experience heat stress and drought; select products with formulations suited to warm-season grasses and high-temperature periods.
When applying any post-emergent herbicide, follow the product label exactly. Perform a test on a small lawn area if you are using a product for the first time, and avoid applying during extreme heat, drought, or windy conditions to maximize effectiveness and protect your turf.