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Finding the best weed killer for St. Augustine grass can feel tricky because St. Augustine lawns need products that match the weed problem without causing unnecessary stress to the turf. The right choice depends on whether you need help with broadleaf weeds, nutsedge, or general weed control, and whether you want a ready-to-spray formula, a concentrate, or a product that also includes lawn feed.
When selecting from the list below, pay close attention to the label directions, the type of weeds the product is designed to control, and whether it is intended for use on St. Augustine grass. It also helps to consider coverage area, application style, and whether you want a selective herbicide for lawn use or a stronger product for spot treatment and non-lawn areas.
Let’s get started!
Our Top Picks at a Glance
| Product | Best For | Buy Now |
|---|---|---|
| Southern Ag 006130 Atrazine St. Augustine Weed Killer 32oz | Targeted St. Augustine weed control | Buy |
| Southern Ag Atrazine St. Augustine Grass Weed Killer, 1 Gallon | Larger-area treatment needs | Buy |
| Hi-Yield Atrazine Weed Killer | Budget-friendly atrazine option | Buy |
Best Weed Killer For St Augustine Grass
1. Best Overall: Southern Ag 006130 Atrazine St. Augustine Weed Killer 32oz
- One quart treats 3,720 sq ft
- Controls Weeds in St. Augustine and Centipede Grasses
- Package Weight: 1.021 kilograms
Southern Ag 006130 Atrazine St. Augustine Weed Killer is a focused option for homeowners looking for a product made specifically with St. Augustine lawns in mind. With a 4.3 rating and a 32 oz size, it offers a practical balance of convenience and targeted lawn use.
This product stands out for shoppers who want a straightforward weed control solution without moving into oversized containers. It is a specialty herbicide, which makes it an appealing pick when the goal is to address weeds in a St. Augustine setting.
If you want one of the most directly relevant options in this lineup, this Southern Ag formula is a strong place to start. It is especially appealing for users who prefer a smaller bottle that is easier to store and apply as needed.
Pros
- Designed for St. Augustine weed control
- Compact 32 oz size
- Solid user rating
Cons
- May not be the best choice for very large lawns
- Specialty use requires careful label reading
2. Best Value: Southern Ag Atrazine St. Augustine Grass Weed Killer, 1 Gallon
- Kills many broadleaf weeds
- Also used in centipede grass
- Provides suppression of crabgrass
Southern Ag Atrazine St. Augustine Grass Weed Killer in the 1 gallon size is a practical option for shoppers who want more volume from the same general product category. Its 4.1 rating suggests it remains a dependable choice for many buyers.
The larger container may be useful for people dealing with repeated treatments or a bigger yard. For St. Augustine grass owners who want a product tied to this lawn type, the gallon format can offer added convenience.
This is a sensible pick for those who want to buy once and have more on hand. If storage space is not a concern, it can be a cost-conscious direction compared with smaller packages.
Pros
- One gallon size for more coverage potential
- Made for St. Augustine grass use
- Good option for repeat applications
Cons
- Higher upfront price than smaller bottles
- May be more than some homeowners need
3. Best For Nutsedge: Ortho Nutsedge Killer for Lawns Ready-to-Spray1
- HOW TO USE: To use this weed control product, connect your garden hose to the weed killer hose sprayer, turn on the water and spray evenly over the area where you want to kill weeds
- WHERE TO USE: This weed spray kills listed weeds not lawns, and may be used on well-established cool-season and warm-season turf grasses
- LAWN WEED CONTROL: This lawn weed killer also controls wild violet and dollarweed, and selectively controls other listed sedge and broadleaf weeds, including dandelion, purslane and spurge
Ortho Nutsedge Killer for Lawns Ready-to-Spray1 is aimed at users who are specifically dealing with nutsedge along with other listed weeds. It carries a 4.3 rating and comes in a ready-to-spray 32 fl. oz. bottle.
This product is suitable for northern and southern turf grasses, which broadens its usefulness for many lawn owners. For St. Augustine grass users who need a weed control product with a stronger focus on nutsedge, it is an attractive option.
The ready-to-spray format adds convenience and removes the need for mixing. That makes it a good fit for homeowners who want a fast, easy application method.
Pros
- Targets nutsedge
- Ready-to-spray format
- Useful on northern and southern turf grasses
Cons
- Not a dedicated St. Augustine-specific formula
- 32 oz size may limit larger jobs
4. Best Weed And Feed: Scotts Turf Builder Weed and Feed5
- WEED AND FEED FOR LAWNS: Apply this combination weed killer for grass and lawn food to your wet lawn when weeds are actively growing and daytime temperatures are consistently between 60°F and 90°F; don't apply more than 2X per year
- WEED KILLER PLUS LAWN FOOD: Scotts Turf Builder Weed & Feed5 weed killer plus fertilizer for grass is a clover and dandelion killer for lawns that also feeds to thicken your lawn and crowd out future weeds
- DO NOT USE ON: Do not use this grass fertilizer for lawns plus yard weed killer on St. Augustinegrass (including Floratam), Dichondra, Lippia, Carpetgrass, and Bentgrass lawns
Scotts Turf Builder Weed and Feed5 combines weed control with lawn fertilizer, making it a two-in-one option for homeowners who want to feed the grass while addressing common weeds. It has a 4.4 rating and covers up to 4,000 sq. ft.
This product is a good fit for people who prefer lawn care products that simplify their routine. Since it is designed to control dandelion and clover while also feeding grass, it may appeal to users looking for a more general lawn-maintenance approach.
For St. Augustine grass owners, the key is to confirm compatibility and application needs before purchase. It is best suited to buyers who want a weed-and-feed style solution rather than a dedicated spot-treatment herbicide.
Pros
- Combines weed control and fertilizer
- Covers up to 4,000 sq. ft.
- Strong product rating
Cons
- Not a specialized St. Augustine weed killer
- May not suit spot-treatment needs
5. Best For Ready-To-Use Spot Treatment: Ortho GroundClear Weed & Grass Killer with Comfort Wand
- FAST-ACTING WEED CONTROL: This weed and grass killer spray absorbs on contact to produce results in just 15 minutes, allowing you to reclaim your outdoor spaces including walkways and driveways, under trees, and in landscape beds
- RAINPROOF IN 2 HOURS: Once dry, the formula becomes rainproof in 2 hours, ensuring that your efforts with the grass and weed killer sprayer are not washed away by unexpected weather
- WEED & GRASS KILLER: This grass and weed spray targets and kills listed weeds and grasses, including dandelions, chickweed, crabgrass, and moss, providing comprehensive coverage for your outdoor spaces
Ortho GroundClear Weed & Grass Killer with Comfort Wand is a ready-to-use spray made for killing weeds and grasses, with a 4.3 rating. It includes a comfort wand, which helps make application more convenient.
This product lists control for dandelions, chickweed, crabgrass, moss, and more. Because it is designed to kill weeds and grass, it is more appropriate for targeted use where you do not need to preserve the treated vegetation.
For St. Augustine grass owners, this is generally the kind of product to reserve for areas where you want total vegetation control, not selective lawn-safe treatment. It is useful when the goal is clearing problem spots quickly and directly.
Pros
- Ready-to-use formula
- Comfort wand included
- Controls a wide range of weeds and grasses
Cons
- Not intended as a lawn-safe selective product
- May not be suitable for use on existing St. Augustine turf
6. Best For Long-Lasting Control: Roundup Dual Action Weed and Grass Killer Plus 4 Month Preventer
- Roundup Dual Action Weed & Grass Killer Plus 4 Month Preventer with Sure Shot Wand kills existing weeds and grass down to the root and prevents new weeds from growing for up to 4 months
- This weed killer and preventer is rainproof in as fast as 30 minutes, and produces visible results in as fast as 6 hours
- Apply to hardscapes and landscapes - along driveways, sidewalks, and patios, along fences, in mulched beds or around the base of well-established desirable plants, shrubs, or trees, and on gravel areas
Roundup Dual Action Weed and Grass Killer Plus 4 Month Preventer combines weed and grass control with a preventer feature. It holds a 4.5 rating and comes with a Sure Shot Wand for easier application.
This product is aimed at people who want both active weed killing and some level of prevention afterward. The 4 month preventer makes it stand out in this list for users focused on reducing future weed pressure.
For St. Augustine grass owners, it is important to use only where appropriate, since this style of product is not meant for broad lawn-safe treatment. It is best suited for non-lawn or carefully selected application areas.
Pros
- Includes a 4 month preventer
- Sure Shot Wand for easier use
- High product rating
Cons
- Not a selective St. Augustine lawn herbicide
- Better for targeted areas than general turf use
7. Best For Extended Prevention: Roundup Dual Action 365 Weed & Grass Killer Plus 12 Month Preventer
- Roundup Dual Action 365 Weed & Grass Killer Plus 12 Month Preventer with Comfort Wand provides one-step weed protection for up to 12 months
- Our weed control kills and prevents many types of tough weeds and grasses for up to 12 months, including clover, dandelion, large and smooth crabgrass, poison ivy, and other broadleaf weeds, grassy weeds and brush
- Roundup Dual Action 365 Weed & Grass Killer Plus 12 Month Preventer with Comfort Wand is rainproof in as fast as 30 minutes and produces visible results in hours
Roundup Dual Action 365 Weed & Grass Killer Plus 12 Month Preventer is built for those who want longer-lasting weed control. It has a 4.4 rating and comes with a Comfort Wand for convenient spraying.
This product is positioned for extended prevention, which may appeal to users wanting longer coverage between applications. It is a stronger choice for non-lawn areas where complete weed and grass removal is acceptable.
St. Augustine grass owners should be careful to keep this product away from areas where the turf needs to remain healthy. It is most useful when the goal is persistent control in problem spots.
Pros
- Designed for 12 month prevention
- Comfort Wand helps with application
- Strong overall rating
Cons
- Not for all lawn-use situations
- May be too aggressive for selective turf care
8. Best For Fast Results: Ortho GroundClear Year Long Vegetation Killer
- Ortho GroundClear Year Long Vegetation Killer with Comfort Wand kills weeds and prevents any re-growth for up to 1 year with a single application
- Fast-acting formula starts working immediately
- Starts to kill weeds and grasses in 1 hour
Ortho GroundClear Year Long Vegetation Killer promises visible results in 1 hour and comes with a continuous spray Comfort Wand. It has a 4.4 rating and is designed to kill weeds and grasses to the root.
This product is suited to users who want fast action and long-lasting vegetation control in areas where no growth is desired. Its year-long control claim makes it a strong contender for driveways, edges, and other non-lawn spaces.
For St. Augustine grass lawns, this is not the kind of product to use across the turf itself. It is best considered for selective problem zones where complete vegetation removal is acceptable.
Pros
- Visible results in 1 hour
- Year-long control claim
- Continuous spray Comfort Wand
Cons
- Not intended for preserving lawn grass
- More suitable for non-lawn areas
9. Best For Broadleaf Weeds: Southern Ag Amine 2,4-D WEED KILLER, 32oz
- Low, economical use rate of 1 to 4 pints per acre
- Controls many broadleaf weeds & woody plants
- Use in turf, pastures, rangeland, ditch banks, fences…
Southern Ag Amine 2,4-D WEED KILLER is a 32 oz concentrate-style option with a 4.4 rating. It is a familiar name for users looking for broadleaf weed control in lawn care settings.
This product may appeal to homeowners focused on common weed issues rather than specialty weed types. The quart size makes it manageable for spot treatment or smaller lawn projects.
As with any herbicide, the key is making sure it matches your grass and weed situation before use. It is best for buyers who want a traditional weed killer format with a practical package size.
Pros
- Good size for smaller jobs
- Suitable for broadleaf weed control needs
- Strong rating
Cons
- Not specifically labeled here as St. Augustine-targeted
- Requires careful application planning
10. Best For Small Spot Jobs: Ortho GroundClear Super Weed & Grass Killer
- TOUGH WEED CONTROL: Ortho Ground Clear Super Weed & Grass Killer1 kills even the toughest listed weeds and grasses down to the root so they don't come back
- WHERE TO USE: Use this weed and grass killer around landscape plants, shrubs or trees; on patios, walkways, driveways, gravel, mulch beds; along fences, around buildings; when preparing landscaped areas or preparing a lawn for renovation
- EASY TO USE: The ready-to-use Ortho GroundClear Super Weed & Grass Killer1 with Comfort Wand weed spray provides continuous spray for easy, targeted application
Ortho GroundClear Super Weed & Grass Killer comes in a 0.5 gal ready-to-use format with a continuous spray wand and a 4.2 rating. It is designed for quick results in hours.
This smaller size makes it a good option for people who only need to treat a limited area. It is convenient for targeted applications where you do not need a large container.
Because it kills weed and grass, it is best used in areas where total vegetation control is acceptable. St. Augustine turf should be protected from contact when using this type of product.
Pros
- Ready-to-use and convenient
- Smaller 0.5 gal size
- Results in hours
Cons
- Not a selective lawn-safe product
- Limited to smaller treatment areas
11. Best For Extended-Use Concentrate: RM43 Concentrated Extended Control Weed Killer
- Concentrated mix with water, add to sprayer
- Serious Weed Control
- Up to one year control
RM43 Concentrated Extended Control Weed Killer has the highest rating in this list at 4.6, and it is designed for extended control. This concentrate format may appeal to people looking for a powerful long-term solution.
The product is a good choice for users who want a concentrated weed killer rather than a ready-to-use spray. It may be especially useful in areas where lasting vegetation control is the main goal.
St. Augustine grass owners should treat this as a non-selective control product and avoid using it where the turf needs to stay healthy. It is best for borders, driveways, and other problem zones.
Pros
- Highest rating in this list
- Concentrated formula
- Extended control focus
Cons
- Not suitable for all lawn applications
- Better for non-turf areas
12. Best Ready-To-Spray Option: Ortho WeedClear Weed Killer for Lawns Ready-To-Spray
- KILL WEEDS NOT YOUR LAWN: Use Ortho WeedClear Weed Killer for Lawns Ready-To-Spray weed killer sprayer to kill weeds down to the root, without harming your lawn (when used as directed); you'll see visible results in hours
- HOW TO USE: To apply this herbicide weed killer, connect your garden hose to the sprayer, slide the switch to 'ON' to begin spraying; visible results in hours; rainproof in 1 hour upon drying; people and pets may enter the treated area after dried
- LAWN FRIENDLY: This weed spray contains three proven ingredients that target common lawn weeds, so it won't harm your grass (when used as directed)
Ortho WeedClear Weed Killer for Lawns Ready-To-Spray is designed not to harm grass when used as directed and treats up to 16,000 sq. ft. It carries a 4.0 rating and is made for lawn use.
This product is useful for homeowners who want a ready-to-spray lawn weed control option. It targets dandelion and clover, making it practical for common lawn weed problems.
For St. Augustine grass, the phrase “when used as directed” matters a lot, so careful label reading is essential. This is a good fit for buyers who want an easier application method and broad lawn coverage.
Pros
- Ready-to-spray format
- Treats up to 16,000 sq. ft.
- Designed for lawn use when used as directed
Cons
- Lower rating than some alternatives
- Still requires careful label compliance
13. Best For Northern Lawns: Roundup For Lawns3 Ready-To-Spray (Northern)
- The Ready-to-Spray applicator is great for broadcast application to your entire lawn, just connect to your garden hose and it's ready to use--covers up to 5,000 sq. ft.
- Kills over 250 weeds, including crabgrass, dandelion, clover, and yellow nutsedge--won't harm your lawn
- Lawn weed killer for use on Northern grasses, including Kentucky bluegrass, perennial ryegrass, fescue, bermudagrass, buffalograss, and zoysiagrass
Roundup For Lawns3 Ready-To-Spray (Northern) is labeled as a lawn-safe weed killer for northern lawns and is designed to kill crabgrass, dandelion, clover, and yellow nutsedge. It has a 4.3 rating.
This product is convenient for users who want a ready-to-spray solution with a lawn-focused approach. The promise to kill weeds without harming the lawn when used as directed is a major selling point.
Since it is labeled for northern lawns, St. Augustine grass owners should be especially cautious before considering it. It is best viewed as a product for those matching the label’s intended lawn type.
Pros
- Ready-to-spray lawn formula
- Targets several common weeds
- Lawn-safe positioning when used as directed
Cons
- Labeled for northern lawns
- Not the most relevant match for St. Augustine grass
14. Best Budget Atrazine: Hi-Yield (33431) Atrazine Weed Killer RTS
- This selective weed killer controls Henbit, Clover, Chickweed and more. See label for full list.
- Intended for use on St. Augustine and Centipedegrass.
- This 32 oz bottle of liquid concentrate weed killer can treat up to 3,720 sq. feet of lawn.
Hi-Yield (33431) Atrazine Weed Killer RTS is a ready-to-spray 32 oz option with a 4.2 rating. As an atrazine-based product, it belongs in the conversation for St. Augustine lawn weed control.
The RTS format makes it simple to use and appealing for homeowners who want convenience. Its smaller size also makes it a practical choice for spot treatment needs.
If you want a straightforward atrazine option without moving up to a larger container, this product offers a balanced middle ground. It is a sensible pick for users wanting easy application and focused treatment.
Pros
- Ready-to-spray convenience
- Atrazine-based formula
- Compact 32 oz size
Cons
- May not suit large coverage needs
- Requires directed use for best results
15. Best Low-Cost Option: Hi-Yield Atrazine Weed Killer
- Atrazine - 4.00%
- Weeds Controlled or Suppressed: Annual Bluegrass (Poa annua), Chickweed (Commonand Mouseear),
- For use in St. Augustine and Centipede grass
Hi-Yield Atrazine Weed Killer is one of the more affordable products in this lineup and has a 4.2 rating. For buyers who want a lower-cost atrazine option, it is worth a close look.
This formula is a simple, straightforward choice for those focused on St. Augustine-style weed control without unnecessary extras. Its appeal comes from its value-oriented positioning.
For homeowners who want a practical product without spending too much, this is a solid final option in the list. It is especially useful for budget-minded shoppers who still want a name-brand atrazine product.
Pros
- Lower price point
- Atrazine weed killer formula
- Good value for budget shoppers
Cons
- May not offer the convenience of ready-to-spray products
- Best suited to users who understand label directions
Buying Guide
Herbicide Type
The first thing to check is whether the product is a selective lawn herbicide, a spot-treatment spray, or a non-selective weed and grass killer. For St. Augustine grass, selective products are usually the safer starting point when you want to treat weeds without damaging the lawn.
Label Compatibility
Always make sure the product label mentions St. Augustine grass or clearly states that it is safe for use when directed. Even a good product can be the wrong choice if it is not intended for your turf type.
Weed Type
Identify what you are trying to control before buying. Some products are built for broadleaf weeds like dandelion and clover, while others are geared toward nutsedge or total vegetation removal.
Application Style
Ready-to-spray products are easier to use, while concentrates can offer better value for larger areas. Choose the format that matches your comfort level and the size of your lawn.
Coverage Area
Check the square footage or bottle size so you do not underspend or overspend for your yard. A small spot-treatment bottle may be enough for localized weed issues, while bigger lawns may need a larger container.
Buy for the Problem You Have
Atrazine products are often discussed for St. Augustine grass, but that does not mean every herbicide is right for every weed issue. Match the product to the weed problem, then confirm it fits your lawn type before applying.
Frequently Asked Questions
What is the best weed killer for St Augustine grass?
The best choice depends on the weeds you are targeting and whether the product is labeled for St. Augustine grass. In this list, atrazine-based options are the most directly relevant starting points for many St. Augustine lawn owners.
Can I use any weed killer on St Augustine grass?
No. St. Augustine grass can be sensitive to the wrong herbicide, so it is important to choose a product that is specifically labeled for use on this turf type or clearly states compatibility when used as directed.
Are ready-to-spray products better than concentrates?
Neither is always better. Ready-to-spray products are easier and quicker to apply, while concentrates often provide more value per ounce and may work better for larger jobs if you are comfortable mixing or using the product as directed.
Should I use a weed and feed on St Augustine grass?
Only if the product label supports your lawn type and your timing is appropriate. Weed and feed products can be convenient, but they are not always the best fit for targeted weed problems in St. Augustine lawns.
What should I check before applying a weed killer?
Read the label carefully, identify your weed type, confirm the turf compatibility, and follow the application instructions exactly. That helps reduce the risk of damaging the lawn or getting poor results.
Conclusion
Choosing the Best Weed Killer For St Augustine Grass comes down to matching the product to your lawn and weed problem. If you want the most direct St. Augustine-focused options, the Southern Ag atrazine products stand out, while other picks in this list offer convenience, broader weed control, or special use cases like nutsedge and long-term prevention.
For the safest and most effective results, always double-check the label before use and choose the product format that fits your yard size and application style. With the right selection, you can handle weeds more confidently and keep your St. Augustine lawn looking better through the season.