Best Post Emergent Crabgrass Killer For St Augustine Grass

#1 · Best Overall

1. Southern Ag Atrazine Quart

• Weight: 2.1 lb
• Form: Spray

Best for: St. Augustine lawn spot treatment.

Why it ranks #1: Its stated use includes St. Augustine, and its description specifically says it suppresses crabgrass while controlling emerged weeds and weeds from seed.

A one-quart bottle treats about 3,720 square feet, giving St. Augustine and centipede lawn owners a defined coverage area for planning weed control. Its atrazine formula controls emerged weeds and weeds from seed, with listed suppression of crabgrass alongside control of many common grassy and broadleaf weeds.

The stated coverage of about 3,720 square feet per quart helps you estimate how much lawn one bottle can address before application. Because the product controls emerged weeds as well as weeds from seed, it covers more than one stage of a weed-control plan. Southern Ag names St. Augustine and centipede grasses as use sites and lists suppression of crabgrass, so it is relevant when those grasses and crabgrass are the concern. Follow label directions and safety precautions.

Skip it if you need a product described as providing full crabgrass control rather than suppression; this listing specifically says it suppresses crabgrass.

A practical option for St. Augustine or centipede owners who want a stated coverage estimate and control of emerged and seeded weeds. Keep the distinction in mind: the product description says it suppresses crabgrass, so match that claim to your control needs.

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

#2 · Larger Format

2. Southern Ag Atrazine Gallon

• Weight: 4.3 oz
• Form: Spray

Best for: Larger-volume atrazine lawn treatment.

Why it ranks #2: It shares the St. Augustine use and crabgrass-suppression claims of the quart option, in a one-gallon format for buyers needing more product.

The one-gallon format gives St. Augustine and centipede grass owners a larger supply of Southern Ag atrazine for lawn weed control. Its listed uses include control of many broadleaf weeds, control of emerged weeds and weeds from seed, and suppression of crabgrass.

The gallon size distinguishes this listing from the smaller Southern Ag bottle and can suit buyers planning a larger-volume application. The product is identified for St. Augustine and centipede grass, with broadleaf weed control plus control of emerged weeds and weeds from seed. Crabgrass is described as suppressed, not as fully controlled, so that wording matters when setting expectations. Follow the product label for application rates and handling directions, which are not specified in the supplied feature details.

Skip it if you need an explicit claim of complete crabgrass control; the product description says it provides suppression.

A sensible match for St. Augustine or centipede owners who prefer a gallon format and want broadleaf and emerged-weed control. Its crabgrass claim is suppression, so choose it only if that distinction suits your lawn-care objective.

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

#3 · Warm-Season Turf

3. Prime Source Celsius WG

• Weight: 18.14 g
• Form: Powder

Best for: Warm-season post-emergent weed control.

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Why it ranks #3: This post-emergent product is described for warm-season turf including St. Augustine, though the supplied details do not name crabgrass specifically.

A 0.226-ounce easy-mix packet gives Celsius WG buyers a measured powder format for post-emergent weed control. The supplied description says its three active ingredients control more than 120 annual and perennial broadleaf weeds and grasses in warm-season turf, including St. Augustinegrass.

The easy-mix packet and powder form make this a compact, portioned product format rather than a large liquid container. Its post-emergent foliar application is intended for weeds already present, and the stated control range covers more than 120 annual and perennial broadleaf weeds and grasses. The warm-season turf list explicitly includes St. Augustinegrass, making that grass a supported fit. The supplied product details do not identify crabgrass among the targets, so check the label for the specific weed and application instructions.

Skip it if you need an explicitly stated crabgrass target; the supplied Celsius WG details describe broad control but do not name crabgrass.

A relevant choice for St. Augustine owners seeking post-emergent control across warm-season turf and many listed weeds. If crabgrass is the specific problem, the supplied description does not name it, so confirm the label target before application.

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

#4

4. Atticus Torocity Mesotrione

• Weight: 8 oz
• Form: Liquid

Best for: Flexible pre- and post-emergent use.

Why it ranks #4: Its 40.0% mesotrione offers pre- and post-emergent activity, but the supplied product details do not confirm St. Augustine compatibility.

Torocity contains 40.0% mesotrione and offers both pre-emergent and post-emergent activity, letting lawn owners address weeds before and after emergence with one concentrate. The product describes use in newly seeded and established turf, while its included pre-marked syringe supports measuring the application amount.

Dual pre- and post-emerge activity gives the application timing flexibility described for Torocity, while its use in newly seeded as well as established turf broadens the situations covered. The 40.0% mesotrione formulation identifies its active ingredient and concentration. An included pre-marked syringe helps measure the concentrate, making preparation more controlled than estimating by eye. The supplied details do not specify St. Augustine compatibility or provide a crabgrass-specific control claim, so verify the label for your intended lawn and weed.

Skip it if you need a listing that explicitly confirms St. Augustine use and crabgrass control; the supplied Torocity details do not make either claim.

A fit for buyers seeking mesotrione with pre- and post-emergent timing and a measuring syringe, especially across newly seeded and established turf. For a St. Augustine crabgrass application, the supplied details leave compatibility and target control unconfirmed.

Listed on Amazon as: Atticus Torocity Mesotrione Herbicide (8oz) – (Compare to Tenacity)

#5

5. Liquid Harvest Mesotrione

• Weight: 8 oz
• Form: Liquid

Best for: Mesotrione concentrate for mixed weeds.

Why it ranks #5: It names crabgrass among target weeds and describes post-emergent use, but the listed suitable grasses do not include St. Augustine.

Mesotrione starts absorbing upon application, giving lawn and turf users a post-emergent option that begins working before full weed death becomes visible. The concentrate targets 46 broadleaf species and grasses, including crabgrass, while its use instructions call for water activation and specify supplemental watering when rain does not arrive.

The stated 2–3 weeks to full weed death sets expectations: absorption starts immediately, but visible completion takes longer. Targeting 46 listed broadleaf species and grasses, including crabgrass, makes the concentrate relevant to mixed weed problems rather than crabgrass alone. Water activation is part of the workflow; if rainfall does not occur within 10 days, the directions call for 0.15 inches of water. The supplied suitable-grass list names centipede, but does not establish St. Augustine compatibility.

Skip it if you need a product whose supplied grass list confirms St. Augustine use; this listing names centipede but does not establish that fit.

Consider this concentrate if your target list includes crabgrass and other listed weeds, and you can manage the water-activation step. Its supplied grass information does not establish St. Augustine compatibility, so that fit is a key boundary for this roundup.

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

#6

6. Liquid Harvest Mesotrione Bundle

• Weight: 8.32 oz
• Form: Liquid

Best for: Mesotrione bundle with surfactant.

Why it ranks #6: This bundle names crabgrass and includes an 8-ounce surfactant, but its supplied grass list does not establish St. Augustine compatibility.

This Liquid Harvest bundle pairs an 8-ounce mesotrione concentrate with an 8-ounce surfactant, giving buyers both listed components for a pre- and post-emergent lawn treatment. The concentrate targets 46 broadleaf species and grasses, including crabgrass, and begins absorbing upon application.

The included surfactant makes this a different package from the concentrate-only listing, while the mesotrione targets 46 broadleaf species and grasses, including crabgrass. The description says absorption begins upon application, with 2–3 weeks possible for full weed death. Water activation is required; if rain does not occur within 10 days, apply 0.15 inches of water. The supplied suitable-grass information names centipede but does not establish St. Augustine compatibility, so check the label for that fit.

Skip it if you need supplied confirmation that mesotrione is suitable for St. Augustine; the listed grass information names centipede but does not establish that fit.

This bundle fits buyers who want mesotrione for listed crabgrass and other weeds, along with an included surfactant. Allow for the stated time to full weed death and water-activation requirement; St. Augustine compatibility remains a label-check boundary.

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

#7

7. The Andersons Meso 4 SC

• Form: Liquid

Best for: Mesotrione for seeding and overseeding.

Why it ranks #7: It lists crabgrass among more than 50 target weeds and has pre- and post-emergent activity, but St. Augustine use is not confirmed.

The Andersons Meso 4 SC is described as safe to use when seeding or overseeding, letting buyers manage listed weeds while establishing new grass, except fine fescue. Its mesotrione liquid provides both pre- and post-emergent control and targets more than 50 common broadleaf and grassy weeds.

Pre- and post-emergent action lets the product address weeds before they grow and after they appear, while the stated seeding and overseeding compatibility supports lawn-establishment workflows with a fine-fescue exception. The target list includes crabgrass, clover, dandelion, foxtail, ground ivy, henbit, and nutsedge among more than 50 weeds. A bottle and syringe are included, supporting measured preparation. The supplied details do not confirm St. Augustine compatibility, so check the label before using it on that grass.

Skip it if you are establishing fine fescue; the listing expressly excludes that grass from its seeding and overseeding compatibility.

A strong candidate for buyers combining weed management with seeding or overseeding, particularly when crabgrass is among the targets. Fine fescue is excluded from the seeding claim, and St. Augustine compatibility is not established by the supplied details.

Listed on Amazon as: The Andersons Meso 4 SC – Mesotrione Pre-Emergent and Post-Emergent Weed Control 8 fl. oz.

#8

8. BASF Drive XLR8

• Weight: 4.2 lb
• Form: Liquid

Best for: Quinclorac concentrate for crabgrass.

Why it ranks #8: Quinclorac targets crabgrass and is rainfast in less than an hour, but the supplied facts do not establish safe use on St. Augustine.

BASF Drive XLR8 uses a water-based formulation for faster plant uptake, giving lawn and turf owners a post-emergent crabgrass treatment with a stated rainfast window. The concentrate also lists broad-spectrum weed control and up to 30 days of residual control.

The water-based formulation is described as supporting faster plant uptake, while becoming rainfast in less than an hour helps define the weather window for application. Its broad-spectrum claim covers grassy and broadleaf weeds, extending use beyond crabgrass. Up to 30 days of residual control may reduce the frequency of repeat applications within that period. This is a 64-ounce liquid concentrate; the supplied details do not confirm St. Augustine compatibility, so use the label to establish whether it fits your lawn.

Skip it if you need confirmed St. Augustine compatibility; this listing does not establish that fit, so consult the product label before treating that grass.

Consider this concentrate if you want quinclorac-based post-emergent crabgrass control, faster uptake, and a stated residual period. The supplied listing does not establish St. Augustine use, making label confirmation essential for the intended lawn.

Listed on Amazon as: BASF Drive XLR8 Crabgrass Killer for Lawn & Turf, Post Emergent Grassy & Broadleaf Weed Control, Active Ingredient Quinclorac, 30 Day Residual, Herbicide, Concentrate 64 Ounce

#9

9. USA Supply Drive Crabgrass Killer

• Form: Liquid

Best for: Mature crabgrass and residual control.

Why it ranks #9: Its quinclorac formula targets crabgrass and claims 30–45 days of residual control, but no St. Augustine compatibility is provided.

Quinclorac provides control of crabgrass even at mature stages, giving buyers a post-emergent option when the weed is no longer newly emerged. This 64-ounce concentrate also lists broadleaf and grassy targets, rainfastness in less than an hour, and 30–45 days of residual weed control.

The mature-stage crabgrass claim addresses a specific challenge for post-emergent treatment, while the broad target list includes foxtail, kikuyugrass, signalgrass, torpedograss, clover, dandelion, and bindweed. A water-based formula becomes rainfast in less than one hour, which can help with application timing around rainfall. Its listed residual period is 30–45 days. The supplied details do not establish St. Augustine compatibility, so check the product label for that grass before choosing it for this lawn.

Skip it if you require confirmed St. Augustine compatibility; the supplied details do not establish it, so check the label before selecting this concentrate.

This concentrate may suit buyers focused on mature crabgrass, additional listed weeds, and residual control. Its rainfastness and residual claims are useful planning details, but St. Augustine fit is not established in the supplied information and needs label confirmation.

Listed on Amazon as: Drive Crabgrass Killer Lawn & Turf, Post Emergent Grassy & Broadleaf Weed Control, Ingredient Quinclorac, 30 Day Residual, Herbicide, Concentrate 64 Ounce w/USA Supply Protective Gloves

#10

10. Fertilome Weed-Out Pro Turf

• Weight: 26 lb
• Form: Granule

Best for: Granular weed control with lawn feeding.

Why it ranks #10: This granular treatment provides pre-emergent crabgrass control and lists several grasses, but not St. Augustine, and it is not a post-emergent crabgrass killer.

A triple-action granule combines broadleaf weed control, crabgrass prevention, and lawn feeding in one application, offering buyers a combined treatment-and-nutrition workflow. The 26-pound bag covers up to 10,000 square feet, and its 25-0-4 formula lists nitrogen and soluble potash.

The granular form and stated coverage of up to 10,000 square feet help buyers plan an application across a sizable lawn. Its triple-action formula kills weeds, prevents crabgrass, and feeds turf, while the 25-0-4 analysis specifies 25% nitrogen, 0% phosphate, and 4% soluble potash. The listed grass types include Kentucky bluegrass, Bahia, Bermuda, and fescue, but not St. Augustine. The supplied description calls this pre-emergent crabgrass control, not post-emergent treatment of existing crabgrass.

Skip it if you need post-emergent treatment for existing crabgrass on St. Augustine; this listing describes prevention and does not list that grass.

This granule suits buyers wanting broadleaf control, crabgrass prevention, and feeding in a single application on a listed turf type. It is not presented as post-emergent crabgrass treatment, and St. Augustine is not in the supplied grass list.

Listed on Amazon as: Fertilome (10928) Weed-Out Pro Turf 25-0-4 Broadleaf + Crabgrass, 26 lbs