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Top 5 Best Weed Killer for St. Augustine Grass (**2020 Review**)

No one wants to see weeds when they’ve got a lawn full of St. Augustine grass, or bermudagrass, bluegrass, fescue, or any other kind of grass for that matter. You want to kill weeds without harming your turf grass.

To successfully control weeds on St. Augustine lawns you need the correct herbicide to kill the weeds.

Deciding which herbicide to get can be difficult. 

Best weed killers for st augustine grass

You need to know which weeds you’re trying to kill (crabgrass, dandelion, chickweed, etc.), how many square feet of lawn you’ve got, and so on. It can be a little confusing at first;  so keep reading and we’ll guide you through the process.

In this Pest Strategies product review you can expect to learn:

  • What are weed killers for St. Augustine Grass?
  • How do weed killers for St. Augustine Grass work?
  • How can you find the best weed killers for St. Augustine Grass?
  • Are weed killers for St. Augustine Grass effective?
  • And our top rated #1 pick for most effective St. Augustine Weed Killer!

If you have an urgent need for weed killer, click here to jump straight to our top pick for the best weed killer for St. Augustine Grass on the market.

ImageProduct
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Southern Ag Amine 2, 4-D Weed Killer
  • Won’t harm crops and lawn grasses
  • A high concentration of active ingredient
  • Covers up to 20,000 square feet
  • Feature 3
  • A high concentration of active ingredient
  • Covers up to 20,000 square feet
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Scotts Turf Builder Weed and Feed Fertilizer
  • Covers up to 20,000 square feet
  • Fertilizes while killing weeds
  • Can be used in different seasons
  • Covers up to 20,000 square feet
  • Fertilizes while killing weeds
  • Can be used in different seasons
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Southern Ag Atrazine St. Augustine Weed Killer
  • Can be used in different seasons
  • Works very fast
  • Versatile on number types of grasses
  • Can be used in different seasons
  • Works very fast
  • Versatile on number types of grasses
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Syngenta Tenacity Turf Herbicide
  • Versatile on number types of grasses
  • Effective post-emergent
  • 5-8 year shelf life
  • Versatile on number types of grasses
  • Effective post-emergent
  • 5-8 year shelf life
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PBI/Gordon Speed Zone Lawn Weed Killer
  • 5-8 year shelf life
  • Quick results even with emerged weeds
  • Beautifies your lawn as it kills weeds
  • 5-8 year shelf life
  • Quick results even with emerged weeds
  • Beautifies your lawn as it kills weeds
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Our Overall #1 Rated Pick

(updated as of 03/26/2020)

  • Won’t harm crops and lawn grasses
  • A high concentration of active ingredient
  • Covers up to 20,000 square feet

This is a selective, post-emergent weed killer. It’s a great choice for killing weeds on St. Augustine grass lawns or around established crops. It gives you good control of weeds such as chickweed, clover, creeping charlie, dandelions, poison ivy, and many others.

It is easy to apply using a low-pressure sprayer such as a backpack sprayer. The active ingredient is Dicamba, a well-known herbicide with an excellent track record of success.

The concentrate in this 32-ounce bottle will give you coverage of 20,000 square feet. After the first application, wait a few weeks then spray it again for the second application and your weed problems will be gone.

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Rating: 97.50

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Rating: 95.70

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Top 5 Best Weed Killers for St. Augustine Grass

  1. Southern Ag Amine 2, 4-D Weed Killer
  2. Scotts Turf Builder Weed and Feed Fertilizer
  3. Southern Ag Atrazine St. Augustine Weed Killer
  4. Syngenta Tenacity Turf Herbicide
  5. PBI/Gordon Speed Zone Lawn Weed Killer

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What Are Weed Killers for St. Augustine Grass?

Weed killers for St. Augustine grass are herbicides that kill weeds without harming the surrounding St. Augustine grass.

Check out the video below for more information on weed killers for your lawn:

Are Weed Killers for St Augustine Grass Effective?

Yes. The caveat is that you have to use them correctly. The main problem with herbicides results when people think “more is better” and add too much concentrate when they’re mixing it.

This winds up burning the grass and creating more problems than you had before.

How To Use A Weed Killer for St Augustine Grass

The label is the law, especially with herbicides, so you need to follow the mixing directions on the label exactly as they’re written. Most yard spraying is done from either a backpack or a tank, which means you’ll do the mixing in the tank or backpack.

Once it’s mixed, start spraying at the foundation of the house and work your way outward in a spiral pattern. If you’re spraying a field, a back-and-forth pattern will work.

Pro-Tip: Whichever you use, always overlap the bands of herbicide by an inch or two.

St Augustine Grass Facts

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Are Weed Killers for St Augustine Grass Safe Around My Pets And Children?

No. Herbicides typically have toxic ingredients that are safe in small amounts but becoming increasingly dangerous as the exposure mounts.

Small children and pets are especially susceptible to toxins. Keep them away from the area being treated until it is completely dry or the dust has settled.

Warning

Weed killers are not safe for use around your pets or children. Please exercise caution when using any of these products.

Best Weed Killers for St. Augustine Grass Reviewed

  • Won’t harm crops and lawn grasses
  • A high concentration of active ingredient
  • Covers up to 20,000 square feet

This is a selective, post-emergent weed killer, making it a great choice for eliminating weeds on St. Augustine grass lawns. It delivers good weed control of broadleaf weeds such as chickweed, clover, creeping charlie, poison ivy, and dandelions.

It’s a concentrate so you can mix it with water to get coverage of 20,000 square feet per 32-ounce bottle. Apply it once with a low-pressure sprayer, wait a few weeks then spray it again to get rid of the last remnants of your weed problem.

Pros

  • Kills many broadleaf weeds
  • Economical
  • Easy to use

Cons

  • Requires two or more applications
  • Variety of coverage areas
  • Fertilizes while killing weeds
  • Can be used in different seasons

Scotts is a well-known brand name with a good track record on lawn care products. It is a weed & feed product that is especially good on Kentucky bluegrass, fescue, ryegrass, centipedegrass, bahiagrass, Bermuda, and zoysia grass. It fertilizes your lawn as it kills the weeds.

The coverage area for each bag is 5,000 to 10,000 square feet and you’ll need a hand-powered spreader to broadcast it. It uses WeedGrip Technology so the particles grip and hangs onto the weeds, including the ones you don’t see.

You can use it just for fertilizing your lawn in spring, summer, and fall, or to kill a wide variety of weeds, making it a truly versatile product.

Pros

  • Easy to apply
  • Popular brand name

Cons

  • Keep kids and pets off the lawn until the dust settles
  • Large 60,000 square feet of coverage
  • Works very fast
  • Versatile on number types of grasses

The active ingredient in this weed killer is atrazine, a selective herbicide used for controlling broadleaf and grassy weeds. It is used to kill emerged weeds on Christmas tree farms, in corn, pineapple, sorghum, sugarcane, and other crops.

It kills many types of broadleaf weeds such as crabgrass and centipedegrass, as well as emerging weeds coming from seeds. You’ll need 8.66 ounces of concentrate per two gallons of water to cover 1,000 square feet, so a one-gallon jug will cover 60,000 square feet.

It can be used on your lawn as well as ditch banks, golf courses, non-crop sites, parks, pastures, and along fence lines. Moreover, it works so fast you’ll start seeing results in just a few hours as the weed begin yellowing.

Pros

  • Very economical
  • Controls emerged weeds
  • Controls weeds coming from seeds

Cons

  • Toxic if swallowed
  • Systemic pre-emergent
  • Effective post-emergent
  • 5-8 year shelf life

The active ingredient is Mesotrione 40%, a systemic pre-emergence and post-emergence herbicide the EPA approved for use on sod farms and golf courses. It is approved for commercial-grade uses as a pre-emergent herbicide as well as a post-emergent one.

It kills a wide range of broadleaf weeds such as bentgrass, carpetweed, chickweed, clover, crabgrass, dandelion, foxtail, goosegrass, henbit, nimble grass, purslane, thistle, yellow nutsedge, and more.

It has a 5-8 year shelf life and this tiny 8-ounce bottle of concentrate will produce 96 gallons of herbicide, using just 1/2-teaspoon of concentrate per gallon of water. That works out to less than a dollar per gallon.

Pros

  • The strong formulation kills many different weeds
  • Excellent price per gallon

Cons

  • The included syringe is difficult to use
  • Excellent amount of coverage
  • Quick results even with emerged weeds
  • Beautifies your lawn as it kills weeds

This is a pre-emergent lawn weed killer that gives you fast results without harming the turfgrass on your lawn. The best time to spray it during cool weather. It kills creeping charlie, clover, and dandelions, to name just a few.

It is highly concentrated so this 20-ounce bottle can provide coverage for an area of 18,000 square feet. Although it’s a pre-emergent, you’ll also notice emerged weeds dying within a day or two of being sprayed.

Pros

  • Doesn’t harm your turfgrass
  • Excellent price point per gallon

Cons

  • Cannot be shipped to AK, DC, MA, NJ, and VT

This selective, post-emergent weed killer is a great choice for eliminating weeds on St. Augustine grass lawns.

It delivers good weed control of many broadleaf weeds. Each 32-ounce bottle gives you 20,000 square feet of coverage.

  • Won’t harm crops and lawn grasses
  • A high concentration of active ingredient
  • Covers up to 20,000 square feet

This herbicide is a great choice for eliminating weeds harming your St. Augustine Grass, so grab a bottle today and begin spraying!

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Final Thoughts On Weed Killers for St. Augustine Grass

No matter what kind of weed you’re facing, there’s a herbicide that will kill it. You need to follow the label directions to get the best results, and when you do, you’ll have a green, weed-free yard in as little as six weeks.

Recommended Reads: Weed Guides

Curious about other weed-related products? Check out our other detailed guides to help you deal with your pest problems.

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