8 Best Weed killers For St Augustine Grass

8 Best Weed killers For St Augustine Grass

Weed and stickers is no less than a nightmare for gardeners and lawn owners. Their presence affect the development of grass shoots and potentially hampers their growth and appearance. That’s why getting rid of weeds and stickers as soon as possible is very important. There are various ways in which you can get rid of them and one of them is using weed killers.

Depending upon the size of your lawn you can decide which killer to buy for example for larger area you there are weed killers specifically designed for larger areas, also there are grass specific weeds killers, for example there are weed killers specifically designed for bermuda grass and St. Agustine grass. St Augustine Grass is one such renowned lawn grass species. It is popularly cultivated for lush green meadows and commercial landscapes. This grass has praiseworthy benefits, making it a top choice for decorating your lawn with bright green carpets.

St Augustine grass has a thick and long texture. It gives a luxurious and dense look to your green space with broad and verdant grass blades. It is a warm-season grass growing mostly in Floria, Texas, and other southern parts of the United States. Due to its bushy turf growth, this grass is naturally weed-resistant. It minimizes weeds taking up any space between its roots.

Unfortunately, despite deterring weed, your st Augustine grass can get exposed to unwanted weed build-up.
You can clear out these weeds by using the best weed killers for st Augustine’s lawn. Highly synthetic or chemical weed killers can burn out your grass. Hang on with us to discover the best weed and feed for st Augustine grass.

What Types Of Weeds Are In St. Augustine grass?

What Types Of Weeds Are In St. Augustine grass?

Weeds have many faces. They may look like normal green plants which easily camouflage within your dense grass coat, but the shape and texture are recognizable.

Weeds also have particular seasons for appearing and vanishing as well. The type of weed growing in your lawn also highlights your soil type and lawn health. This acts as a major factor in deciding the best weed killer for St Augustine grass.
The most common weeds that target St Augustine grass are:

  • Dollar Weed
  • Bermuda grass
  • Poa Annua
  • Dallis grass
  • Henbit
  • Crabgrass
  • Clover
  • Chickweed

These weeds occasionally show up and spread over your magnificent St Augustine grass. Without further ado, let’s right away see some tried and tested best weed killers for st Augustine grass.

Best Weed Killer For St Augustine Grass

No beating around the bush! Let’s get down to the business. We have briefly explained all top herbicides for St Augustine grass, inclusive of its plus points and drawbacks. Rip that weed off your St Augustine lawn.

1. Scott’s Turf Builder Weed killer

Through my trial and error, I’ve discovered that Scotts is the highest rated lawncare brand that manufactures a popular range of herbicides for killing weeds. Firstly, this weed killer comprises atrazine, which is a vital herbicide present in any best weed killer for St. Augustine grass.

I’ve found that it effectively kills weeds without harming the grass’s health. Atrazine wipes out most types of weeds, including stubborn clover and dollar weeds. Furthermore, I’ve noticed that it also works as a pre-emergent by preventing the birth of new weeds by feeding the grass blades.

On top of that, I believe that this herbicide for St. Augustine grass is not just limited to a single purpose; it simultaneously nourishes and strengthens grassroots so that they can withstand hot temperatures and scarce water conditions.

It is tailor-made for Florida grass species and other southern areas. It comes in a standard formulation as well. I’ve also found that the NPK (Nitrogen, Phosphorous, Potassium) ratio of Scott turf builder is 29:0:10. The high quantity of nitrogen accelerates plant growth and enhances greenery.

Potassium builds a strong immune system for the grass against diseases. This weed killer has a granule structure which can be easily spread over the lawn. After evenly distributing the weed killer, I recommend flushing out your lawn with water to initiate the herbicide absorption process into the soil. In my experience, this is the most important step for using weed killers.


  • Effective atrazine composition
  • Two-fold advantage of killing weeds and nurturing grass
  • Feasible and budget friendly
  • Usable both as a pre-emergent and post-emergent weed killer
  • Abundant nitrogen and potassium for lush green and well-maintained lawns.
  • Floratam friendly


  • Some weeds may escape and continue to grow even after using this weed killer.

2. Southern Ag 006130 Atrazine St. Augustine Weed Killer

Based on my firsthand experience, I can say that Gardeners’ favorite best weed killer for Augustine grass is a reliable choice. Its atrazine formulation works wonders on weeds without harming the St Augustine turf.

This liquid weed killer is specifically designed for southern lawns and grass species, with both pre-emergent and post-emergent properties. It effectively eliminates ingrown weeds in the lawn and destroys budding weeds from their roots. This stops new weeds from germinating and spreading in your grass carpet.

It can cover an area of up to 3720 sq. feet. However, this weed killer cannot be sprayed directly, as the liquid herbicide is highly concentrated and can harm your turf instead of killing weeds. It needs to be diluted with water and then spread uniformly on your lawn or target spots. One drawback is the high chemical content in this herbicide, which can have unfavorable effects on your family and pets.


  • Fulfils Pre-emergent and post-emergent needs
  • Destroys not only upper-level weeds but also the roots
  • Value for money
  • It can cover 14000 sq. feet of area in just one gallon of product


  • High doses of chemicals can prove to be hazardous

3. Natural Armor Weed and Grass Killer

Hands down, this is the best natural weed killer for St Augustine grass. It is prepared from natural and environmentally friendly ingredients which are safe for your family and pets. It contains zero percent Glyphosate.

Along with being green, it provides fast action and visible results within hours. It puts an end to 250 varieties of weeds effectively. This liquid weed killer is concentrated with anti-weed agents, which act beneficially on weeds.

There’s no rocket science in using this best herbicide for st Augustine grass. Simply attach the spray valve, aim at the areas you wish to wipe out unwanted weeds, and just spray the mixture evenly.

There is no hassle of mixing or diluting the liquid. It is ideal to spray this on a sun-kissed day with at least 65°F temperature. Make sure there are no rain forecasts. After applying the weed killer, you will see the weeds disappearing within 24 hours; that’s the speed and effectiveness of this best weed killer. Make sure to stay away from the lawn for a particular period while the weed killer is doing its job. It might be risky to come in contact with weed killer while it hasn’t gotten completely absorbed by the lawn.

You can use this weed killer in any location where you don’t wish for any unpleasant vegetation, like near flowerbeds, fruit and vegetable gardens, lawns, Pools, walk stones, fence edges, and so on. You get all one advantage in a single weed killer.


  • Ease of use without any messy mixing
  • Multipurpose weed killer in all areas
  • 24-hour outcome with quick effect
  • Planet-friendly and contains no harmful chemicals like glyphosate
  • Safe for pets and kids


  • The sprayer can malfunction and leak the weed killer from the bottle
  • The effect of the liquid may not be long lasting

4. Roundup weed killer for Lawns

My findings show that Round Up weed killers is one of the best weed killers for St Augustin grass. It is designed specifically for southern grass lawns and acts dominantly on stubborn weeds, finishing them off from their roots for complete removal.

It gets rid of the most common weed species like clover, dollar weed, dandelion, and over 93 types of weed. The liquid composition does not harm your grass or plants. It only targets unwanted greens.

This weed killer is really effective as it guarantees to kill the roots of the weeds so that they do not regrow. The ready-to-spray mechanism allows easy application across the grass and aids in the spot treatment of weeds. It provides an area coverage of 6000 sq. feet.

On top of that, it is rainproof for about 4 hours which shields the liquid from diluting in the rain. This weed killer comes in various packaging and properties, such as ready-to-spray, concentrated, and ready-to-use refills.

It also has a policy of replacement or money back if the product fails to satisfy the consumer. Be cautious, as this weed killer contains toxic chemical content, which can cause ill effects on pets and children. Keep them away while using the weed killer. Read the directions for use before applying it over your lawn for safety.

I personally think that Round Up weed killers is a great option for homeowners who are looking for an effective and easy-to-use weed killer for their St. Augustine grass lawns


  • Fast Kill on contact action
  • Root targeting, which prohibits renewal
  • No harm to St Augustin grass turf
  • Safe and suitable for all southern lawns, including delicate centipede and Floratam
  • Simple spray application to cover maximum area at once


  • High amount of harmful chemicals noxious for children, pet dogs, cats, etc.

5. The Andersons Barricade Professional-Grade

Drawing from my experience, here is the top quality, granular, best pre-emergent weed killer for St Augustine grass. The granules are small-sized to provide more particle coverage per square inch. It contains prodiamine, an active herbicide that finishes 30 species of weeds, including henbit, crabgrass, foxtail, and much more.

It is a trustworthy weed killer which effectively prevents frequent growth and seasonal mushrooming of weeds all year long.

Coming to its magic mechanism, this weed killer has innovated with The Anderson’s patented Dispersible Granular (DG) Technology which enables the small granules to break down into thousands of microparticles on water contact.

This allows the absorption of herbicide into the deep soil layers, where it defends weed seed germination and prevents any further development of weeds. Being a pre-emergent, the timing of using the weed killer matter critically. It is crucial to understand that this weed killer will only prevent upcoming new weeds and not eradicate the existing weeds from your lawns.

For St Augustine grass, apply this weed killer in the early spring season before the 4-inch-deep soil heat onsets at 55 degrees Fahrenheit to prevent the germination of annual summer weeds. Further, you can apply it again in the mid-fall or autumn season to discourage the growth of winter weeds in southern lawns.

Irrigate the lawn after spreading granules for activating the dispersible herbicide. Note: If you have fostered new seeds, wait for 60 days or a second mowing session before using the weed killer else. It might backfire and deactivate your grass seeds instead.

I personally have used this weed killer for my St. Augustine grass lawn and have been very happy with the results. I have found that it is very effective at preventing weeds from growing, and it has also helped to keep my lawn looking healthy and green. I would definitely recommend this weed killer to anyone who is looking for a reliable and effective way to control weeds in their St. Augustine grass lawn.


  • Cost-effective for large lawns
  • Area coverage up to 12880 sq. feet with 40 lbs of weed killer
  • Two applications are enough to keep weeds away from your lawn
  • Effective Andersons patented Dispersible Granular (DG) Technology which travels down the soil to kill each early-stage weed.
  • Small granules allow wide coverage by every inch


  • Only applicable in two seasons
  • Might kill your new grass seeds if the timing is not appropriate.

6. Spectracide Weed killer

Another Atrazine powered the best herbicide for st Augustine grass. This excellent weed killer gives two benefits – a pre-emergent and a post-emergent liquid.

It kills the existing weeds from the lawn without harming your turf. Along with this, its on-contact action reaches within the soil to clear out weed seeds and also destroy weed roots completely.

In short, it gives total weed control to you with just a simple spray-on system. Atrazine works like a charm for eliminating unpleasant weeds and budding weed buds underneath the soil.

The quick flip hose end flip attaches easily to your garden hose for providing a uniform spread on the lawn. It is ideal for 3720 sq. feet of area. This weed killer is ready to spray and use in all seasons where the temperature is below 90 degrees Fahrenheit. Do not use it during high-temperature hours.


  • Presence of powerful atrazine
  • Easy set-up and application
  • Special southern grass formulation
  • Pre-emergent and post-emergent utility.


  • Time-taking process

7. Ortho Weed B Gon Weed Killer

As per my expertise, Ortho weed B Gon killer is a remarkable spray-on herbicide that is convenient to use with a garden hose and is one of the best weed killers for St Augustine grass, including Floratam.

This weed killer is a master of its craft as it can annihilate more than 250 types of stubborn weeds found in various lawns and grass species. It eliminates weeds not just superficially, but from deep roots to effectively prevent their return.

If the given directions are followed accurately, this weed killer is safe for your grass and does not leave any aftermath on its quality. However, keep in mind that results won’t be visible immediately after application, and it takes around 5 – 7 days for the herbicide to kill the weeds and produce the desired outcome.


  • Kills 250 and above weed variety
  • Steady grip control and ready-to-spray action
  • Just needs 1 hour to be rainproof
  • Suitable even for Floratam (a hybrid of St Augustine grass)


  • Users report low power and unsatisfactory results
  • Weak built and packaging

8. Hi-Yield Atrazine Weed Killer

The last bestseller on the list is Hi-Yield Atrazine Weed killer, which is a pre-emergent as well as a post-emergent weed killer liquid. It comprises 4% atrazine which is a strong weed-deterring herbicide.

It is ideal for preventing Poa Annua, Henbit, and chickweed, which are found mostly in St Augustine grass and Centipede Grass Lawns. This dual-action weed killer successfully removes all unwelcome weed growths from roots within and also stops the germination of new weed seeds below the soil layers.

You accomplish two objectives at once, which saves time and ensures 100 percent weed deletion from the lawn for the present time and future both. A quarter of this weed-killer liquid can treat 3720 sq feet of area. All these features make this best weed killer for St Augustine grass competent in the market.


  • High atrazine content
  • No harm to grass blades
  • Rips off weed from roots
  • Restricts emergence of new weeds
  • You get value for money


  • Might cause discoloration on excessive use in one area.

How To Decide The Best Weed killer For St Augustine grass

We have seen the list of best weed killers for st Augustine grass. Now the question is which one to choose and how?
Weed killers are classified based on their purpose and core property.

It has two distinct uses, which bring us to two broad categories of weed killers: pre-emergent weed killers and post-Emergent weed killers. Your weed growth stage and situation will decide your choice of the best weed killer.

Below table gives you a complete picture of pre-emergent weed killer and post- emergent weed killer

CriteriaPre-Emergent Weed KillersPost-Emergent Weed Killers
DefinitionA type of herbicide that is applied before weed seeds germinate and emerge from the soilA type of herbicide that is applied after weeds have emerged from the soil
TargetTargets weed seeds that have not yet germinatedTargets weeds that have already emerged from the soil
EffectivenessHighly effective at preventing weed growthHighly effective at killing existing weeds
TimingApplied before weed seeds germinate, typically in early spring or fallApplied after weeds have emerged, typically during the growing season
PersistenceCan remain active in the soil for several weeks or monthsTypically breaks down relatively quickly in the soil
ApplicationApplied evenly over the soil surface and watered inApplied directly to the foliage of the weed
SelectivityGenerally non-selective, meaning they can harm desirable plants and grassesCan be selective or non-selective, depending on the type of herbicide used
Environmental impactCan be harmful to beneficial insects and other non-target organismsCan be harmful to beneficial insects and other non-target organisms if not used properly
CostRelatively inexpensiveCan be more expensive than pre-emergent herbicides
MaintenanceRequires regular application to prevent weed growthRequires repeated applications as weeds continue to emerge
Overall purposeUsed as a preventative measure to stop weeds before they growUsed to control and eliminate existing weeds

And, here is more information about pre-emergent and post-emergent weed killers to make your purchase decision easy.

1. Pre- Emergent Weed Killer

Most people take action after the damage has been done. But if you are a cautious gardener and suspect any small weed growths in your lawn, you can begin early. Prevention is always better than cure. Pre-Emergent Weed killers are used to eliminate weed seeds that haven’t yet sprouted above the soil.

It forms a chemical layer below the soil and disrupts the germination stage of weeds, which stops their growth then and there at the earliest. It is usually applied over St Augustine grass during the late winter or early spring period when it’s dormant. Pre-emergent weed killers should be a part of your daily lawn care to keep the weeds at bay. Keep track of weed season and take steps accordingly.

2.  Post- Emergent Weed Killer

Post-emergent weed killers are used to treat existing weeds that are visible in patches between your bushes, flowers, and grass. They have a kill-on-contact property that allows the removal of weed growths from the lawn.

When you see weed sprouting in your lawn, use post-emergent and pre-emergent weed killers together to destroy mature weeds and prevent any further weed development from seeds. Best weed killers have both pre-emergent and post-emergent usage that takes care of all your worries single-handedly.


Weeds come to your lawn without an invitation, but you can choose to say goodbye to them. It’s just about finding the best weed killer for your St Augustine lawn that removes internal and external weed traces. Try finding an atrazine-rich weed killer, as it takes stronger action on hard weeds. With the use of a best weed spreader you would get more better results.

Stay up to date with your lawn care and begin the anti-weeding process at the perfect time to end on an expected note. Timing is very important for removing weeds fully from your lawn. Any amount of leftovers can cause a fresh wave of weeds yearly on your lawn.

Plan and use pre-emergent as well to avoid any future situations. Just follow the directions and tips, and you are good to go. Say Hello to beautiful, healthy lawns.


The best time to apply weed killer to St. Augustine grass is in the spring and fall seasons. The grass is not under stress when the weeds are actively growing season.

It is best to apply weed killer before mowing St. Augustine grass. Applying weed killer before mowing allows the herbicide to be absorbed more effectively by the weeds.

The time it takes for weed killer to work on St. Augustine grass will depend on the specific weed killer used. Generally, you can expect results of weed killer within 1-2 weeks.

Several natural weed killers are safe for use on St. Augustine grass, including weed killers containing vinegar, salt, and corn gluten meal.

It is generally recommended to wait at least 4-6 weeks after planting St. Augustine grass before applying weed killer. This allows the st. Agustine grass to establish a strong root system.

The frequency of weed-killer applications will depend on the severity of the weed problem. It is generally best to apply weed killer as needed to prevent the establishment of weeds in st. Agustine grass.

In most cases, applying a weed killer and fertilizer is not recommended at the same time, as this can increase the risk of damage to the grass. It is best to apply a weed killer and fertilizer separately.

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