The Best Weed Killer For St Augustine Grass

St Augustine Grass is a dense, lush, and very popular type of grass used in lawns across the Southern United States.

This type of grass does best in warmer environments like Florida or Texas, but it can also thrive in other parts of the US if properly cared for.

Also known as carpet grass, St Augustine Grass is beloved for a few reasons. First, it grows thickly and with much broader blades than a number of other types of grasses. This gives it a dense, rich appearance when it comes to the sod.

St Augustine Grass is also a popular choice amongst home owners because it is a type of grass that deters weeds naturally. It is tolerant of salt, which makes it an excellent grass for homes near the sea, and because it grows so thick it often overcrowds competing weeds and plants.

Unfortunately, no matter how thick or lovely your St Augustine Grass is, it can still be susceptible to a weed or two from time to time.

So, what is the best weed killer for St Augustine Grass and how can you protect your lawn and keep weeds away in the future?

Keep reading to find out!

But First, What Are The Most Common Weeds In St Augustine Grass?

1 st augustine grass up close
Although St Augustine Grass does grow dense and is hardy against lawn problems, it is still susceptible to developing weeds. 

Although St Augustine Grass is known for competing with weeds and being one of the best grasses to deter weeds, it’s still possible for weeds to crop up.

It will be important that you consider a few factors when looking into the best weed killer for St Augustine Grass, including your region, the season, and the type of weeds you are dealing with in your lawn.

Different weeds can tell different stories about your lawn and the type of soil underneath. It can also tell you about your lawn’s health and help you more proactively target the weeds, which can help when choosing the best weed killer for St Augustine Grass.

But with so many weeds in the world to contend with, it can be difficult to pinpoint the types of weeds you’re dealing with.

What Is A Weed? 

By definition, a weed is a plant that is not supposed to be in certain man-controlled gardens, lawns or agricultural areas.

This basically means that a weed is just a plant growing in the wrong location. Some weeds can be more aggressive than others, and invasive weeds are especially problematic when they are fast growing, choking out other plant life in the area and spreading out of control.

Although not everyone will have the same idea of what a weed is, it’s important that you have a good idea of what kinds of weeds can attack St Augustine Grass in your location so you can better control them.

The Most Common Weeds In St Augustine Grass

There are quite a few weeds that can crop up in St Augustine Grass, and different weeds will depend on your location.

However, and as we mentioned above, it’s important to try and identify the types of weed you’re dealing with when looking for the best weed killer for St Augustine Grass. The most common types of weeds you might contend with in this type of grass can include:

  • Henbit
  • Clover
  • Chickweed
  • Dollar Weed
  • Poa Annua
  • Dallisgrass
  • Crabgrass
  • And Bermudagrass

The above types of weeds can be frustrating to discover in your yard, but luckily there are weed killers available to help. Of course, even the best weed killer for St Augustine Grass comes with its share of pros and cons.

Let’s learn more.

The Best Weed Killer For St Augustine Grass – Pros And Cons

2 clover in grass
Clover is a common weed that can sprout in a number of grasses, not just St. Augustine grass. 

The pros and cons of the best weed killer for St Augustine Grass can vary and change depending on your location, the types of weeds you are dealing with, and how much weed killer you’ll need to use in order to manage your problem.

One of the pros of using the best weed killer for St Augustine Grass is that weed killer, also known as herbicide, is easy to use. It works quickly and effectively and many herbicides can help target a number of different weeds in a single application.

Another advantage to using the best weed killer for St Augustine grass includes expense. Most weed killer products are inexpensive and long-lasting, meaning when applied correctly they can continue to kill weeds for long periods of time, saving you money and work in the long run.

However, some disadvantages of using a weed killer or chemical herbicide might include the environmental impact of using chemical herbicides and the accidental spread of chemicals to other areas.

While some weed killer products are made with natural ingredients, others contain harsh ingredients that can be harmful to the environment and ecosystem, especially if not used carefully.

It’s also important to keep in mind that weed killers can be dangerous for children and pets, so you’ll need to make sure you read the instructions carefully before applying the best weed killer for St Augustine Grass to your yard if you have youngsters or animals.

With all of that noted, it’s now time to talk about the best weed killer for St Augustine Grass that can help to target, remove and even prevent the above listed weeds.

Weed Killer For St Augustine Grass – Best Post-Emergents And Pre-Emergents

3 a drawing of a weed killer applicator
Both pre-emergents and post-emergents should be used together to effectively kill and prevent weeds in the grass. 

If you’re here looking for the best weed killer for St Augustine Grass, you’ve likely already found weeds sprouting in your lawn. If this is the case, then the type of weed killer for St Augustine Grass you should be looking for will be called a post emergent.

Post emergent herbicides are designed to target and kill weeds that have already sprouted above the surface of the lawn and that are now visible to you.

When you see weeds in the lawn, it will be important to use both a post emergent and a pre emergent, which targets weeds that have yet to sprout.

Although weeds can crop up anytime of year, there is a general weed season that you can try and predict when it comes to your specific lawn and location. These factors are often based on climate, region and season. And, as previously discussed, different types of weeds will favor different types of soil.

Still a pre emergent typically works best when applied in late winter or early spring, as most weeds sprout up in mid spring or early summer. But how does pre emergent work?

This type of weed killer for St Augustine works by killing the weeds before they erupt from the soil. It covers the soil below the grass in a chemical layer that stops the weeds from germinating and spreading.

If you apply pre emergent to weeds you can already see, you will not have great results. That’s why using a pre-emergent should be considered a routine part of lawn care and maintenance as opposed to simply using a weed killer or post emergent alone.

Some herbicides provide both pre-emergent and post emergent care for weed control in one, though some do one or the other.

Which ones do we recommend? Let’s take a look at some of the best weed killer for St Augustine Grass when it comes to chemical herbicides.

Southern AG St Augustine Weed Killer Herbicide

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First on our list of weed killer for St Augustine Grass is a weed killer specifically created for southern grasses. This product is designed to treat up to 3,720 square feet and kills both the weed and the root on contact.

This weed killer for St Augustine Grass is a unique weed killer because it works as both a pre emergent and a post emergent by killing sprouted weeds and weed seedlings below the surface. It also helps to terminate the weeds at the root.

This product works for most common weeds that are known to grow in St Augustine Grass as well as Centipede grasses.

However, this product does contain chemicals that could be harmful to people and pets. Be sure to read the directions carefully and use it only as directed.

Scotts Select States Turf Builder

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Another weed killer for St Augustine grass we would recommend is Scotts Select States Turf Builder. As its name suggests, this product is designed for selected regions of the US, (in this case the South), where St Augustine Grass is most common and most popular.

This weed killer treats up to 5,000 square feet and controls and kills weeds known to commonly be problematic for southern grasses like St Augustine grass.

Roundup For Lawns

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Last, we have Roundup For Lawns. Again, this product is specifically designed for southern grasses including centipede grasses and St Augustine Grass. It specifically targets some of the most common weeds including dandelion, clover, dollarweed, and up to 93 other types of weeds that may be causing you issues.

This product works by killing the weeds at the root. It comes in a few different options including a concentrate or a ready to spray option. You can also order it with a wand to help with application, or simply order it as a refill to add to your own spray or application container.

We like this weed killer for St Augustine Grass because it specifically targets and kills weeds without harming your lawn, which should give you peace of mind when applying it. Of course, as with all weed killers on this list, remember that Roundup is made with chemical ingredients that could be toxic to people and pets.

Be sure to use it only as directed and keep it out of reach of children.

With that being said, if you would prefer to use a weed killer for St Augustine Grass that doesn’t contain chemical ingredients, you also have that option as well.

Let’s talk about organic weed killer for St Augustine Grass below!

Best Organic Weed Killer For St Augustine Grass

4 a child playing in the lawn
If you have children or pets, you might prefer to look for an all natural method for getting rid of weeds. 

Because so many weed killer for St Augustine Grass options contain harsh chemicals, organic gardeners can shy away from traditional weed control methods in an effort to stay as green as possible.

The good news is that there are some organic options you can turn to if you would prefer to use natural methods to control weeds.

Some of our favorite organic options for weed killer for St Augustine Grass are listed below.

Natural Armor Weed and Grass Killer Concentrate

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Natural Armor provides an environmentally safe weed killer option for spot treating your lawn and keeping your St Augustine Grass looking its best. With that being said, this is a weed killer that should not be used directly on the grass and is best formulated as a perimeter spray or spot treatment.

The product will kill St Augustine Grass as well on contact, so apply it carefully and only target specific weeds and areas you do not want weeds or grass to grow.

Natural Elements Weed Killer

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Another natural herbicide we would recommend is made by the Natural Elements Store. This weed killer for St Augustine Grass is safe to use around children and pets as it does not contain harsh chemical ingredients.

It is effective on most broadleaf weeds, however it does contain vinegar as its active ingredient and again should be used more as a spot treatment for weeds in St Augustine Grass as opposed to an all over spray or application.

This is because vinegar can be harsh on grasses and will kill the grass or surrounding vegetation it comes into contact with.

Espoma Organic Weed Preventer

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As we’ve mentioned a few times now, one of the keys to ensuring your lawn is healthy and weed free is to use both a pre-emergent and a post-emergent together. There are natural pre-emergents you can use when looking for a good weed killer for St Augustine grass, and one of the ones we would recommend is Espoma Organic Weed Preventer listed above.

This product works on many common weeds and uses corn gluten meal to suffocate seedlings before they are able to sprout.

Because this product uses organic ingredients like corn gluten meal, it is safe to use around children and pets and there is no wait time for children or pets to play in your yard once this product is applied.

However, we should note that you should refrain from using this weed killer for St Augustine Grass if you are also seeding a new lawn, as this product will inhibit the growth of these seeds as well.

For the best recommended use, it’s suggested to apply this weed killer for St Augustine grass bi-annually. This would include one time in early spring and again in early fall.

How To Make Your Own Weed Killer For St Augustine Grass At Home

5 a spoon of salt
Mixing salt and water will make an effective weed killing formula that is great for targeted weed control.

When looking for a good weed killer for St Augustine Grass, you may have noticed that many contain harsh chemical ingredients that could be harmful or even dangerous for people, pets and the environment.

While some weed killers for St Augustine grass do provide natural options, there are other alternatives you can consider, including making your own weed killer at home.

Here are some of the best home methods you can use when it comes to weed killer for St Augustine Grass.

Pull The Weeds By Hand

Perhaps the biggest no-brainer on this list is to consider pulling the weeds by hand. Of course, this is a tedious task depending on the size of your lawn and the number of weeds causing you problems.

For most of us, getting rid of weeds is already time consuming and frustrating, and pulling weeds by hand is the last way we want to spend our Sunday afternoons.

With that being said, if you do have just a few weeds in your lawn and you would prefer not to use any chemical methods, pulling weeds by hand is always an option.

Spread Corn Gluten Meal 

Corn gluten meal may not kill already sprouted weeds, but it can work as a DIY pre-emergent and stop weeds from growing. In fact, most organic pre-emergent products contain corn gluten meal as their active ingredient, as we noted above.

This product works by creating a barrier over the lawn and drying out a new weed from the seed, stopping its growth altogether.

Try Target Spraying With White Vinegar & Liquid Dish Soap

Are you interested in a DIY weed killer recipe? Here is what you’ll need:


  • 1/4th Cup Liquid Dish Soap
  • 1 ¼ Cup of White Vinegar
  • 3 Drops of Wintergreen Essential Oil
  • 3 Drops of Orange Essential Oil
  • 3 Drops Cinnamon Essential Oil
  • 1 spray Bottle


Combine the above ingredients into a spray bottle and then shake the bottle until the liquid inside is sudsy. Be very careful when using this recipe as a weed killer for St Augustine grass, as this combination can also kill the grass and other surrounding vegetation.

This should be a targeted weed treatment only, and you’ll need to carefully spray weeds individually for the best results.

Make A Salt Spray To Target And Kill The Weeds

Making a DIY salt spray is another method you can use for homemade weed killer for St Augustine grass. However, like using vinegar and soap, using salt should be done with caution and only applied directly to the plants you wish to kill.

To make a salt spray, use a 3 to 1 ratio of salt and water and combine this mixture into a spray bottle. Mix the solution until the salt is dissolved, then spray it directly on the weeds.

Cover Weeds With Newspaper

Last, you always have the option of covering weeds with newspaper or some other material that will block out the sun.

Like most plants, weeds need a combination of sun and water to survive. If you starve them of sun, it will only be a matter of time before they die.

Again, this will need to be a spot treatment method and is not an ideal weed killer for St Augustine grass solution for those with a large volume of weeds on their lawn.

Other Tips For Keeping St Augustine Grass Weed Free In The Future

6 grass with dew on it
Allowing your grass to grow a bit longer than usual will help to keep it healthy and reduce weed growth. 

Keeping your lawn healthy and lush will reduce the amount of time you’ll need to take when it comes to weed and pest control in the future.

In fact, the recipe for keeping your lawn weed free and insect free is to simply keep it healthy and happy.

Caring for your lawn doesn’t have to be difficult, but it does take some time, planning and dedication.

When it comes to St Augustine grass, a good routine can go a long way. The good news is that St Augustine grass is one of the easiest lawns to care for. Weed growth is relatively less common than in other types of grass and this type of grass tolerates shade well.

Here are a few other tips and tricks from experts you can use to help nurture your St Augustine Grass and keep your lawn looking its best.

Keep A Good Schedule For Watering and Fertilizing 

Watering and fertilizing are givens to any healthy lawn, but understanding the schedule in which to do so is important. The amount in which you water and fertilize your lawn and how often, can determine how healthy and vibrant your lawn grows.

Infact, overwatering and overfertilization can actually have a negative impact on St Augustine grass and lead to problems including pest issues and dead patches.

There should be a happy medium when it comes to this routine, but that perfect amount will depend on your specific region.

Experts recommend that you pay attention to soil temperature, climate, season and the amount of traffic in your lawn when choosing how often to water and fertilize. If you’re not sure how to begin looking into how to best care for your specific lawn, the best place to start is by researching your specific city or state.

Allow Your Lawn To Grow Longer Than Usual

Another way you can help ensure a healthy and vibrant lawn is by allowing your lawn to grow a bit longer than you usually would.

Many lawn enthusiasts tend to enjoy mowing their lawn short, but this can actually lead to your lawn being more vulnerable to problems like weed growth. In fact, experts recommend even going so far as to adjust your mower so you are leaving your grass about a quarter of an inch longer each time you mow.

You might also consider going a few extra days between mows to allow your lawn that extra time in the sun.

Use A Year-Round Pest Control To Manage Insects 

An unhealthy lawn can leave room for serious weeds, and one of the biggest contributors to an unhealthy lawn are going to be insects. Grubs in particular can cause problems in your St Augustine Grass, but so can many other pests including rodents.

It’s important to implement a year-round pest control regimen to help keep your lawn healthy and reduce not only pests like insects and animals from destroying your grass, but also to prevent providing an ideal environment for weeds to begin to grow and compete.

Control Tatch Growth 

Thatch is a common problem in St Augustine Grass, especially if this grass is watered and fertilized heavily. Tatch is undecomposed plants, stems, roots and other organic matter both living and dead that has built up in your lawn over time.

You can control and manage thatch by mowing with a vertical mower or using a rotary mower on its lowest setting to remove the lawyer of tatch growing.

Removing tach is important, especially when it comes to weed and pest control. A lawn that is thick with thatch is more likely to develop weed growth and pest problems.

Aerate When Needed 

Last, don’t skimp on proper aeration. Aerating your lawn will help to keep it healthy which, as we now know, reduces chances of pest infestations and weed growth.

There are plenty of benefits to aerating, as it in helps increase the strength of your turfgrass roots, it reduces the compaction of soil in heavily trafficked areas, it reduces water runoff, it improves the intake of fertilizers, and it allows for better water intake into the soil, amongst other things.

And there you have it – all the different methods you can use when it comes to weed killer for St Augustine Grass along with our expert tips and tricks for how to best care for this type of lawn.

We hope this has been a helpful guide and that you’ll be on your way to a gorgeous lawn soon. Now we want to hear from you! Tell us what you think about weed killer for St Augustine Grass in the comment section below.

Happy gardening!

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