Best Weed Killer For St Augustine Grass: 10 Options Compared

#1 · Best Overall

1. Southern Ag Atrazine 32 oz

• Weight: 2.1 lb
• Form: Spray

Best for: St. Augustine spot-treatment concentrate.

Why it ranks #1: For St. Augustine and centipede lawns, this quart treats 3,720 square feet and controls emerged weeds as well as weeds from seed.

A quart treats up to 3,720 square feet, giving St. Augustine and centipede lawn owners a defined coverage target for planning weed control. Southern Ag Atrazine also controls emerged weeds and weeds from seed, so its stated action covers more than weeds already visible at application time.

The 32-ounce concentrate is intended for St. Augustine and centipede grasses, making its labeled grass range a useful starting point for lawn selection. Its stated coverage of 3,720 square feet helps estimate how much lawn one quart can treat. The product controls many common grassy and broadleaf weeds, including emerged weeds and weeds from seed, and provides crabgrass suppression. As a concentrate, it requires following the label’s application directions rather than treating the bottle as a ready-to-spray product.

Skip it if you need a ready-to-spray bottle; Ortho Weed B Gon is specifically labeled ready-to-spray for St. Augustinegrass.

Choose this Southern Ag concentrate if your lawn is St. Augustine or centipede and you want stated coverage plus control of emerged weeds and weeds from seed. Follow the label for application directions and safety.

Listed on Amazon as: Southern Ag 006130 Atrazine St. Augustine Weed Killer 32oz Specialty Herbicide, Light Tan

#2 · Named Weed Coverage

2. Hi-Yield Atrazine Weed Killer

• Weight: 2.2 lb
• Form: Liquid

Best for: Measured concentrate for spring lawns.

Why it ranks #2: Its label lists Henbit, Dollarweed, Chickweed, Clover, and Sandspur; the 32-ounce concentrate treats up to 3,720 square feet of St. Augustine.

A 32-ounce bottle treats up to 3,720 square feet, giving St. Augustine and centipede owners a clear lawn-area reference for this Hi-Yield concentrate. Its listed weeds include henbit, clover, chickweed, dollarweed, and sandspur, and the label supports use in dormant and growing seasons.

This liquid concentrate targets St. Augustine and centipedegrass, with controls for both emerged weeds and weeds from seed. The 3,720-square-foot treatment figure helps plan lawn coverage, while dilution instructions vary by lawn dimensions and grass type, so application requires checking the label. The product can be applied during dormant or growing seasons on established turf, and early spring is identified as the best-results timing. Shake the bottle, dilute as directed, then apply evenly with a sprayer or watering can.

Skip it if you want a ready-to-spray product without concentrate dilution; Ortho Weed B Gon is labeled ready-to-spray for St. Augustinegrass.

Choose Hi-Yield if you want a measured concentrate for established St. Augustine or centipedegrass and can follow its variable dilution directions. Early spring is the stated best-results timing, though seasonal use also includes dormancy.

Listed on Amazon as: Hi-Yield (33430) Atrazine Weed Killer, 32 oz

#3 · Ready-to-Spray Pick

3. Ortho Weed B Gon

• Weight: 2.3 lb
• Form: Spray

Best for: Ready-to-spray Floratam lawns.

Why it ranks #3: This ready-to-spray product is labeled for St. Augustine, including Floratam, lists 250-plus weeds, and treats up to 2,500 square feet.

The ready-to-spray bottle is labeled for St. Augustinegrass, including Floratam, so owners can apply without preparing a concentrate mixture. Ortho lists control of more than 250 weeds and coverage up to 2,500 square feet, while rain-proof performance begins one hour after application.

The easy-grip control supports broadcast application, making this format suited to treating weeds across a lawn rather than mixing a separate spray solution. Its stated coverage is up to 2,500 square feet, and the label specifically includes Floratam within its St. Augustinegrass use. Ortho says it kills listed weeds down to their roots and becomes rain-proof in one hour. Those features suit buyers who value simple application and a shorter wait for rain resistance; use as directed to protect the lawn.

Skip it if you need a concentrate with a stated 20,000-square-foot coverage; Spectracide Weed Stop lists that area per bottle.

Ortho fits Floratam and other St. Augustinegrass owners who want ready-to-spray broadcast use, root-level weed claims, and one-hour rain resistance. Its listed coverage tops out at 2,500 square feet.

Listed on Amazon as: Ortho Weed B Gon Weed Killer for St. Augustinegrass Ready-To-Spray, 32 oz

#4

4. Image Weed Killer for Southern Lawns

• Weight: 2 lb
• Form: Liquid

Best for: Floratam-focused southern lawns.

Why it ranks #4: Made for southern lawns including St. Augustine and Floratam, this ready-to-spray liquid targets broadleaf weeds and describes fast visible results.

Visible results in hours distinguish IMAGE Weed Killer for Southern Lawns, while its listed use specifically addresses Floratam lawns. The ready-to-spray liquid targets tough broadleaf weeds in southern grasses, including St. Augustine, Bermuda, and Zoysia, with claims of control down to the root.

The product’s southern-lawn focus includes St. Augustinegrass and specifically calls out Floratam, helping owners match the formula to a named turf type. Ready-to-spray application avoids the concentrate-dilution step, and instructions say to spray evenly on the lawn for weed control. The listed fast action brings visible results in hours, while the root-kill claim addresses weeds beyond surface appearance. Its stated lawn-safety claim applies when used as directed, so label instructions remain central to application.

Skip it if you need an explicit square-foot treatment estimate; Ortho Weed B Gon lists coverage up to 2,500 square feet.

IMAGE suits southern lawn owners, especially those with Floratam, seeking a ready-to-spray approach and visible results in hours. Follow the label and spray evenly; the supplied details do not state coverage area.

Listed on Amazon as: Image Herbicide Weed Killer for Southern Lawns, 32 Oz

#5 · Granular Weed and Feed

5. Fertilome St. Augustine Weed & Feed

• Weight: 25.6 lb
• Form: Granules

Best for: Weed control plus lawn feeding.

Why it ranks #5: The 15-0-4 granules combine fertilizer with pre- and post-emergent weed control and cover 5,000 square feet of St. Augustine lawn.

A 15-0-4 fertilizer blend combines feeding with pre-emergent and post-emergent weed control, making this Fertilome granule a two-part lawn-care option. It is intended for St. Augustine, centipede, and Zoysia lawns, covers 5,000 square feet, and is recommended for early-spring application.

The weed-and-feed format pairs fertilizer with both pre-emergent and post-emergent herbicide action, so one application addresses lawn feeding and weed control. Its 15-0-4 blend is specified for St. Augustine, centipede, and Zoysia, and the stated 5,000-square-foot coverage helps plan treatment across a lawn. Early spring is recommended for improved lawn health and season-long weed defense. The grass restriction matters: the product must not be used on Bermuda or other Northern grasses, so turf identification is essential before applying.

Skip it if you have Bermuda grass; Southern Ag Atrazine is listed for St. Augustine and centipede, not as a Bermuda weed-and-feed.

Fertilome fits owners of St. Augustine, centipede, or Zoysia who want weed control and a 15-0-4 fertilizer in granules. Apply in early spring as recommended, and exclude Bermuda and Northern grasses.

Listed on Amazon as: Fertilome (13917) St. Augustine Weed & Feed 15-0-4, 25.6 lbs

#6

6. Envu Celsius WG Packet

• Weight: 18.14 g
• Form: Powder

Best for: Single-packet warm-season post-emergent.

Why it ranks #6: Celsius is described for warm-season turf including St. Augustine and controls more than 120 annual and perennial broadleaf weeds and grasses.

The 0.226-ounce easy-mix packet offers a compact way to prepare Celsius WG for post-emergent weed control. Envu describes control of more than 120 annual and perennial broadleaf weeds and grasses in warm-season turf, including St. Augustinegrass, making its turf compatibility explicit.

Celsius WG is a post-emergent, foliar-applied herbicide with three active ingredients, connecting application to weeds already present on the turf. Its stated control covers more than 120 annual and perennial broadleaf weeds and grasses in warm-season turf types such as St. Augustinegrass. The easy-mix packet and included product label support a measured preparation workflow, but this listing identifies a single 0.226-ounce packet. Buyers planning repeated treatments should account for that single-packet format and follow the label.

Skip it if you want two seasonal treatments in one pack; Bug And Blade Celsius WG supplies two packets for a spring-and-fall cycle.

Envu Celsius WG fits St. Augustine owners seeking a post-emergent foliar herbicide in an easy-mix packet. The listing is for one packet, so consider that limit when planning coverage or repeated applications.

Listed on Amazon as: Prime Source Celsius WG – 0.226 oz Easy Mix Packet-Post Emerge Weed Control

#7 · Larger Concentrate Size

7. Southern Ag Atrazine Gallon

• Weight: 4.3 oz
• Form: Spray

Best for: Gallons for warm-season lawns.

Why it ranks #7: This gallon-size listing is specifically for St. Augustine and centipede grass and states control of emerged weeds and weeds from seed.

The one-gallon format gives St. Augustine and centipede lawn owners a larger container of Southern Ag Atrazine for their weed-control routine. Its listed action includes broadleaf weeds, emerged weeds, and weeds from seed, with crabgrass suppression also specified for this product.

Southern Ag identifies this spray herbicide for St. Augustine grass and also notes use in centipede grass, which helps buyers check whether their lawn matches its stated use. The listed weed action covers many broadleaf weeds and weeds from seed, while crabgrass suppression adds a separate stated benefit. The one-gallon container distinguishes this offering from smaller bottles, though the supplied product details do not give a treatment-area figure for this size. Follow the label directions for use.

Skip it if you want a stated coverage figure on the product details; Southern Ag 006130 lists 3,720 square feet per quart.

This is a fit for St. Augustine or centipede lawn owners seeking the one-gallon Southern Ag format and its listed broadleaf and seedling weed control. Check the label for application directions and coverage.

Listed on Amazon as: Southern Ag Atrazine St. Augustine Grass Weed Killer, 1 Gallon

#8

8. Bug And Blade Celsius WG

• Weight: 12.75 g
• Form: Granule

Best for: Two-treatment warm-season program.

Why it ranks #8: The two-treatment pack claims coverage up to 4,000 square feet and lists crabgrass, dollarweed, and clover among more than 120 weeds.

Two treatments are packaged for a spring-and-fall weed-control cycle, with stated coverage up to 4,000 square feet. Bug And Blade’s Celsius WG two-pack targets more than 120 weeds, including crabgrass, dollarweed, and clover, offering a seasonal schedule in one purchase.

Each packet is described for a two-gallon application, and the two-pack provides two applications per season. That setup supports an early-spring treatment as weeds emerge followed by a late-summer or fall cleanup, rather than relying on a single application. The supplied details state coverage up to 4,000 square feet and list more than 120 target weeds, including crabgrass, dollarweed, and clover. This format is best matched to buyers prepared to follow the stated two-treatment timing and coverage limits.

Skip it if you need a ready-to-spray single-pass option; Ortho Weed B Gon is labeled ready-to-spray for St. Augustinegrass.

This Celsius WG two-pack fits buyers planning spring and late-season weed treatments across up to 4,000 square feet. Its stated schedule and coverage are useful boundaries; apply each packet according to its label.

Listed on Amazon as: Celsius WG Herbicide 2-Pack with Bug And Blade Weed ID Card

#9

9. Spectracide Weed Stop Concentrate

• Weight: 3 lb
• Form: Liquid

Best for: Large-area broadleaf concentrate.

Why it ranks #9: Its concentrate treats up to 20,000 square feet and lists more than 200 weeds, but the supplied listing does not specifically confirm St. Augustine use.

A 40-ounce bottle treats up to 20,000 square feet, making Spectracide Weed Stop a concentrate for buyers covering a broad lawn area. It lists more than 200 weeds, including dandelion, chickweed, and clover, and claims root kill with overnight results.

The concentrate requires mixing with water according to its directions, while its listed coverage of up to 20,000 square feet gives buyers a substantial treatment area to plan around. Spectracide names major broadleaf weeds such as dandelion, chickweed, and clover, with more than 200 listed weeds overall. The formula is rainproof if rainfall or watering occurs six hours after application. Application timing is also bounded: the supplied facts specify daytime temperatures between 60° and 85°F.

Skip it if you need a St. Augustine-specific label; Ortho Weed B Gon explicitly names St. Augustinegrass, including Floratam.

Spectracide fits buyers seeking broad listed weed control across a large lawn area and who can mix concentrate and observe its temperature window. Check its label for turf suitability and application instructions.

Listed on Amazon as: Spectracide Weed Stop for Lawns Concentrate 40 Oz, Concentrate Formula

#10

10. Liquid Harvest Mesotrione Bundle

• Weight: 8.32 oz
• Form: Liquid

Best for: Mesotrione concentrate users.

Why it ranks #10: This concentrate targets 46 weed species and includes surfactant, but the supplied compatible-grass list does not confirm St. Augustine use.

This bundle pairs eight ounces of mesotrione concentrate with an eight-ounce surfactant, giving lawn-care users two components for a pre- or post-emergent routine. It targets 46 broadleaf species and grasses, while the stated activation requirement makes watering or timely rainfall part of the workflow.

Mesotrione is described as absorbing upon application, though full weed death may take two to three weeks, setting a clear expectation for visible results. The product supports pre-emergent and post-emergent use and targets 46 species, including crabgrass, clover, chickweed, and dandelion. Water activation is required; if rainfall does not occur within ten days, the directions call for 0.15 inches of water. The listed grass compatibility includes centipede, but the supplied details do not establish St. Augustine use.

Skip it if you need explicitly listed St. Augustine compatibility; Ortho Weed B Gon names St. Augustinegrass, including Floratam.

Consider this bundle if mesotrione’s listed weed targets and pre- or post-emergent use match your lawn program. Account for water activation and the stated two-to-three-week interval for full weed death.

Listed on Amazon as: Liquid Harvest Mesotrione Bundle – 8 Ounces – Mesotrione Concentrate (Compare to Tenacity) – Pre and Post-Emergent Weed Killer for Lawn and Turf Grasses with 8oz Surfactant