Best Weed Killer For St Augustine Grass

Top 7 Best Weed Killer For St Augustine Grass

Ian Mutuli
Updated on
Ian Mutuli

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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As we all know, grasses are an essential aspect of our yards, and they give the ultimate attraction. Maintaining them is not so easy because we have to care for them pretty well to look good. However, there are different types of grasses, which are used to keep our lawn or yard beautiful, and today we are going to discuss St. Augustine grass (Stenotaphrum secundatum) and how to maintain them well from weed. It is a common warm-season grass that grows in U.S. Department of Agriculture plant hardiness zones.

Applying weed killer on St. Augustine grass is one of the easiest ways to keep the weeds under control, but like other things, it also comes with a list of deliberations. The first and foremost important thing is to choose the best weed killer that will not abolish your grass and make them safe.

Accordingly, we have prepared a list of the best weed killers for St. Augustine grass to make this process easier. In addition, we will discuss the quality of the enlisted products along with their advantages and drawbacks. I hope this will ease your way to find the best option for your St. Augustine grass and keep them safe.

Top Options for Best Weed Killer for St Augustine Grass

1. Green Gobbler Vinegar Weed Killer

Green Gobbler 20% Vinegar Weed & Grass Killer | Natural...
  • KILLS WEEDS & GRASS FAST - Eliminate any type of weed in just a...
  • SAFE TO USE ANYWHERE - Perfect for residential, commercial,...
  • CERTIFIED FOR ORGANIC USE - Completely eliminates and desiccates...
  • POWERFUL FORMULA - NO potentially cancer-causing chemicals....
  • 30-DAY MONEY BACK GUARANTEE - If you are not pleased, call or...

According to science, Vinegar is one of the best home-based regular weed killers that you can ever expect. The product from Green Gobbler, which we are talking about, is made with Vinegar. Because of the perfect blend of water and Vinegar, this weed killer is the easiest and safest way to prevent weeds. But you have to be careful and not apply it to the turfgrass you are raising. You have to handle it with care and make sure that you spray this on the weeds only or the grown-up grasses. Other highlighted features of this weed killer are as follows,

Key Features

  • It kills weed and grass very fast.
  • Use on crabgrass, dandelions, clover weeds, white clover, moss, etc.
  • This product is safe to use anywhere you want.
  • This weed killer is certified for organic uses.
  • It has one of the most potent formulae for preventing weed in this lineup
  • 30 days money-back guarante

Green Gobbler Vinegar Weedkiller is an organic and useful product, and it can be recommended for users, but it is not for commercial use. Therefore, this is not your option if you want to use it for a large space or big lawns. But this is one of the best choices for household use and doing it carefully.


  • Tremendously operative on any weed20% acetic acid destroy weeds faster
  • Safe for pets and kids100% organic
  • It is glyphosate-free
  • It can also kill moss


  • It cannot be used for commercial use
  • Vinegar does not cover up large space
  • In the long run, it can be questioned

2. Scotts Select States Turf Builder

Scotts Turf Builder Triple Action, Weed Killer and...
  • Scotts Turf Builder Triple Action is a 3-in-1 formula that kills...
  • Built-in lawn weed killer controls existing dandelion, clover,...
  • Prevents crabgrass for 4 months (will not kill existing...
  • Apply combination weed killer and preventer plus fertilizer to...
  • One 20 lb. bag of Scotts Turf Builder Triple Action covers 4,000...

Scotts Turf Builder is a weed killer and condenses your lawn to help crowd out future weeds. Regular feedings deliver the nutrients to your lawn to look at their best and endure the stresses of heat, deficiency, and family commotion. You can use it on St. Augustine grass (including Floratam), centipede, zoysia, and carpetgrass lawns. You have to use it when grass and weeds are actively growing. If we search for the main features of this weed killer, then we will see the following points,

Key Features

  • Kills dollar weed, clover, and other lawn weeds
  • It feeds grass to crowd out future weeds
  • Builds strong, deep grassroots to strengthen against heat and famine
  • Not for use on Bermuda grass

Finally, watching Scotts Turf Builder's features is a better product, especially for St. Augustine grass, which is our main concern. So, this product is highly recommended for preventing the grass weed problem.


  • Perfectly works for St. Augustine grass
  • Easy to use
  • Easy to speared
  • Works fast


  • Bit costly
  • Not for all kinds of grass type

3. The Andersons Pro Turf Barricade

The Andersons Barricade Professional-Grade Granular...
  • Apply this product only in EARLY SPRING and FALL
  • Barricade professional-grade pre-emergent weed control is...
  • Contains 0.48% of the active ingredient prodiamine - Labeled to...
  • Trusted by top turf care professionals to prevent problem weeds...
  • DG Pro formulation allows for more particles per square inch of...

The Andersons Pro Turf Barricade weed control is one of the best and most user-friendly, effective gritty weed remover products on the market. This thing is considered to help demolish over 30 grass and broadleaf weeds in recognized turf grasses, lawns, landscapes, and ornamental beds. It comes with .48% of the active ingredient Prodiamine. If we talk about the other highlighted features of this weed controller, then we have the following points,

Key Features:

  • Allows for more units per square inch of chemical
  • Designed to prevent weeds and will not assist in eliminating existing weeds
  • It has a fast working capacity

Overall, The Andersons Pro Turf Barricade weed control process is effective indeed but has some bindings as well. Nevertheless, it is highly recommended in the fall season because it has some seasonal issues and works perfectly in fall conditions. Thus, it is undoubtedly a quality product in the weed killer lineup.


  • Easy to use
  • Easy to spread
  • Perfectly works after application
  • Value for money


  • It stops weed growth but does not kill the existing
  • It has a seasonal fact, does not work effectively in all seasons

4. Natural Armor Weed & Grass Killer (2594 4.0)

Natural Armor Weed and Grass Killer All-Natural...
  • ✅CONTAINS NO GLYPHOSATE - Natural, Concentrated Formula For...
  • ✅ EASY TO USE – People & Pet Friendly. Ready To Use, Just...
  • ✅ PLACES TO USE – Use Anywhere You Don’t Want Weeds and...
  • ✅ FAST ACTING – See Results In Hours and Even Greater Results...

Natural Armor Weed & Grass Killer is another organic product on our list. It is a natural product and not harmful. You can use this killer anywhere you don’t want to see the weed. Such As, Around Flower Beds, Shrubs and Trees, Barns, Driveways, Edging, Fence Lines, Foundations, Gravel Areas, Mulch Beds, Overgrown Weed Areas, Parking Areas, Patios, Pavers, Pool Areas, Rock Walls, and Pathways, Walkways, Wells & Water Systems. Its multipurpose application makes this thing desirable because it will indeed affect the weed and remove them. Let us check out the features.

Key Features

  • This thing has no glyphosate
  • You can use this killer anywhere
  • It is really fast-acting; you will find the results in front of your eyes
  • Without asking any question 30 days money-back guarantee

So, Natural Armor Weed & Grass Killer has valuable features, and it is recommended for the right choice because it is natural and can prevent the weed you want.


  • Free of harmful chemicals
  • Safe for the users and surrounding people
  • Multipurpose use
  • It is straightforward to use


  • Advertised as a fast killer, but it is not

5. Quali-Pro Prodiamine 65 WDG

Quali-Pro Prodiamine, Pre-Emergent Herbicide, 5 lbs,...
  • PRE-EMERGENT HERBICIDE: Quali-Pro's Prodiamine 65 WDG provides...
  • FEATURES & BENEFITS: Excellent tank mix partner with fertilizers...
  • USE SITES: Nurse, Landscape, Turf, Trees, Golf Courses
  • EFFECTIVE AGAINST: Annual bluegrass (Poa annua), Henbit,...
  • ACTIVE INGREDIENT: Prodiamine 65%

Quali-Pro’s Prodiamine 65 WDG delivers pre-emergent grass and broadleaf weed control. Malleable applying method permits for both spring and fall use, providing season-long crabgrass control. This weed controller is available in a 5-pound bottle. Looking at the key features, we found the following points,

Key Features

  • It is a professional type of product
  • Multipurpose use
  • Effective against Annual bluegrass (Poa annua), Henbit, Knotweed, Chickweed, Spurge, Foxtail, Goosegrass
  • It has Prodiamine 65% active ingredients

After watching all the features and advantages of Quali-Pro’s Prodiamine 65 WDG, we can consider this the right product, but the major drawback is the price and slow effectiveness. Therefore, it is not a good option for fast working ability, but it is recommended as the right product.


  • Knock out weed early
  • Prevents and restrict weed for a long time
  • Easy to use and maintain.
  • It takes a very short time to set up
  • It heats up steadily.


  • Not a weed killer, it’s a preventer
  • A little bit of pricey

6. Doctor Kirchner Natural Weed Killer

Doctor Kirchner Natural Weed & Grass Killer (2.5...
  • A natural weed killer Made from ocean salt water, commercial...
  • Our non selective ready to spray Natural Weed & Grass Killer is...
  • No Mixing, No Glyphosate and No Hormone Disrupting Chemicals

Doctor Kirchner Natural Weed Killer always wants you to take care of your garden and ensure that they are free from weed. This Natural Weed Killer quickly and safely takes care of all the weeds and does the treatment required for the land. Since it is made with ocean water and food-grade vinegar, it is safe for pets and kids. Besides, it also has some valuable features, and they are as follows,

Key Features

  • Made with natural and less harmless ingredients.
  • Typically not used on the lawn.
  • Provide an alternative to harmful herbicides and toxic weed treatments.
  • No Mixing, No Glyphosate and No Hormone Disrupting Chemicals
  • Using this product directly is safe for Pet, kids, and the environment

From all sides, Doctor Kirchner Natural Weed Killer is one of the finest products available in the market, and it has some drawbacks, but they can be ignored because it has more effectiveness.


  • Simple and user friendly using
  • A fantastic product according to the users
  • Polished finish that gives a classy look.
  • Cools down quickly and auto shuts off
  • Three years warranty


  • Sprayer quality is not up to the mark

7. Southern Ag Atrazine 

Southern Ag Atrazine St. Augustine Grass Weed Killer, 1...
  • Kills many broadleaf weeds
  • Also used in centipede grass
  • Provides suppression of crabgrass
  • Controls emerged weeds and weeds from seed

Southern Ag Atrazine St. Augustine Grass weed killer is another favorite and practical thing in this line-up. It is one of those weed killers that can appropriately target the weeds and not kill the grass. One of the best choices, regarding that this is a better weed killer for St. Augustine Grass. It has a lot of right sides.

Key Features

  • This weed killer kills many broadleaf weeds
  • It can be used in centipede grass
  • It provides suppression of crabgrass
  • Controls emerged weeds and weeds from seed
  • One gallon of spray

So, the product details and Southern Ag Atrazine St. Augustine Grass weed killer's advantages seem moderate. Still, within a reasonable price, this is a better option for maintaining our lawns. Of course, you might find a better option according to your need, but this is recommended in our list.


  • It is very safe to apply on the grass
  • Kills over 200 broadleaf weeds
  • Work fast
  • Reasonable price


  • Acts faster but do not remain for long

Varieties of St Augustine Grass

In the scope of understanding the best weed killers for St Augustine grass lawns, it is also vital to know there are different varieties of this grass. Here are the highlights of the different St Augustine grass varieties:

  • Floratam St Augustine, which is considered the most drought-resistant variety.
  • Seville, a variety that is characteristically dwarf with a finer texture than the floratam. Seville Augustine lawns tend to present a blue-green impression with excellent tolerance to shade, salt and wide pH ranges.
  • Sapphire, a St Augustine variety known to be prone to fungus and has a blue-green color.
  • Bitterblue Augustine, whose lawns tend to thrive as the warm temperatures arrive like in the early spring and early summer. Such St Augustine lawns are tolerant to cold and shade while maintaining a darker impression of blue-green.
  • Palmetto St Augustine, which has the best tolerance to drought and cold. Additionally, the Palmetto St Augustine lawns have the highest tolerance to shade among all Augustine varieties.

Also, in light of maintaining the best lawn care for your St Augustine grass varieties, you will find various similarities of this grass to the types of Bermuda grass and Buffalo grass. For instance, these three grass types have similar growth patterns of running carpets. Individually, Buffalo grass is the easiest to maintain and the hardest, but it also invades the most. On the other hand, St Augustine grass is the hardest and most sensitive to grow, while Bermuda grass is an average of its predecessors.

In comparison, the three different grass types thrive better in different climatic zones. Ideally, there are 13 hardiness zones that are differentiated from the lowest to extreme temperatures. During winter, Bermuda grass and St Augustine grass die off, while buffalo grass remains green throughout the year.

Most Common Weeds in St. Augustine Grass

Having understood the nature and varieties of St Augustine grass, we will proceed and identify the most commonly found weeds in St Augustine grass. Notably, different weeds in St Augustine grass vary depending on the climate of the different growing zones. Below are the most common weeds in St Augustine grass:

  • Dandelions. These weeds can be identified through its bright yellow flowers, making it easy to spot.
  • White clover. This weed type is also identified through its flowers which are pink in color with white petals.
  • Goosegrass. Also known as silver crabgrass, it is one of the known grassy weeds known to have long and thick leaves. As you control weeds, goosegrass can be identified through its silver or white color around the roots.
  • Dollarweed. This type of weed is most common in wet conditions. Therefore, you may encounter this weed during the growing season when watering is done often. It is also known as pennywort.
  • Crabgrass. This star-shaped weed presents long and thick leaves with an outward growth pattern and shallow roots.

Other common weed types include henbit, chickweed, dallisgrass, and Poa Annua. Notably, if you intend to have a pure St Augustine lawn, then it can be said that other grasses such as Bermuda grass and Buffalo grass can also feature as weeds. In the end, identifying the type of weeds commonly found in St Augustine grass helps in choosing the most appropriate weed killers for leaving your lawn weed-free.

Pre-Emergent vs. Post Emergent Herbicides

You can control and kill weeds in St Augustine grass by using pre-emergent herbicides or post-emergent herbicides. But before applying either of these weed killers, it is always best to not apply any weed killer during the first growing season to avoid damaging newly sodded St Augustine grass. Therefore, before you start using a lawn herbicide, it's always best to ensure that your grass is healthy and adequately watered. Even so, this premise doesn't mean to downplay the importance of weed killers.

Going back to the concepts of pre-emergent and post-emergent herbicide applications, these two herbicide types are differentiated by their application times. During the first growing season or application, we recommend applying half the recommended amount of both a pre or post-emergent herbicide per square feet area. This half application technique should continue until you have mowed your St Augustine grass thrice.

Nonetheless, there are other common weeds that are tough to control through the half-dosage or single-spray techniques. Some other common weeds will also have a lot of seeds in the soil, leading to a continuous spread across your St Augustine grass lawn. As such, it is essential to distinguish between a pre-emergent herbicide and a post-emergent herbicide.

Pre-Emergent Herbicide

A pre-emergent herbicide is applied only at the start of the growing season. In particular, timing is very important for a pre-emergent herbicide since it kills weeds in St Augustine grass by preventing their germination. Characteristically, a St Augustine grass lawn is known to be sensitive to herbicides containing the active ingredient of 2,4-dichlorophenoxyacetic acid. This selective-herbicide active ingredient kills weeds that are broadleaf and can be used to regulate plant growth.

Accordingly, the best pre-emergent herbicide for St Augustine lawns should control weeds safely, and you should be able to read a product's label for its ingredients. Some of the known safe pre-emergence herbicides for a St Augustine grass lawn include Dithiopyr, Oryzalin, Prodiaminem, Isoxaben, Pendimethalin, and Benefin+ Trifluralin. The listed names of pre-emergence herbicides represent the primary active ingredient names which come in different names under different companies.

Therefore, applying a pre-emergent herbicide is necessary as a weed preventative measure in addition to regular lawn care. In particular, a safe pre-emergent herbicide with a suitable active ingredient should be applied at the right time, which is at the beginning of a growing season. Notably, a pre-emergence herbicide is necessary for any grass lawn.

Post-emergence Herbicides

An alternative to a pre-emergent herbicide is a post-emergence herbicide, which is applied when runners can visibly be seen to spread. Also, post-emergent herbicides are applicable once unwanted growth such as that of broadleaf weeds and perennial grasses starts to develop in St Augustine grass. Accordingly, you should consider post-emergent herbicides that kill weeds safely without damaging sod and those that kill weeds that you're targeting.

Unlike a pre-emergent herbicide, a post-emergent herbicide is applied to control or kill weeds after they have emerged rather than prevent weed growth. In particular, a post-emergent herbicide works best on young weeds for comprehensive control. Therefore, the best weed killers in this category should be reapplied 10 days to two weeks after the first post-emergent application.

Moreover, the active ingredient in post-emergent herbicides best kills weeds before the greening-up stage when the grass starts to grow to avoid damaging a grass lawn. Therefore, if you are late to apply your post-emergent weed killer, you can use these selective herbicide types when your lawn has fully greened to avoid damage. Besides the St Augustine grass, post-emergent herbicides should also be applied to other grasses like Bermuda grass as part of their lawn care.

Combined Postemergence and Pre-Emergence Herbicides

As part of making weed control easy in St Augustine grass, you can find pre-emergent and post-emergent herbicide combinations. For instance, you can find a combination of pre-emergence herbicide isoxaben and post-emergence herbicides of 2,4-D + mecoprop. Such a combination is considered safe for well-developed St Augustine grass.

Several herbicides in this spectrum can damage newly sodded areas due to their pre-emergence weed-killing components. Examples of safe combined weed killers include Bromoxynil and MCPA based herbicides. Conversely, you should avoid combined weed killers with Dicamba as the active ingredient. In terms of application, if broadleaf weeds reappear after spraying, we recommend repeating the spraying after two weeks or as per the product's specifications.

Homemade Weed Killers For St Augustine Grass

The use of post-emergent and pre-emergence weed killers is the most recommendable technique to control weeds found in St Augustine Grass. Nonetheless, several herbicides in these categories can be pricey, making them inaccessible. Therefore, this section will present some homemade natural methods that can be used for St Augustine weed control.

Also, some pre-emergent and post-emergence solutions might be harmful to the environment, people and pets. Accordingly, resorting to more natural techniques such as mixing salt and water might kill weeds safely. In light of safe and affordable weed killing techniques, here are a few known home solutions for St Augustine grass weeds:

  • Pulling weeds by hand. This technique is the simplest yet the most tedious for weed control. For instance, you can use this technique to control broadleaf weeds in southern grasses. However, this method can be frustrating depending on diverse weed problems prevailing in your lawn. Ideally, weeds are best pulled out when they're young since their roots aren't firm and deep into the soil.
  • Target-application of liquid dish soap and white vinegar. This method is particularly delicate as this combination can also kill your St Augustine grass alongside other surrounding vegetation. This DIY solution isn't best for square feet application such as pre-emergent and post-emergence solutions and only works well under small-scale weed targeting.
  • Covering weeds. This weed-killing method uses the starving approach by depriving the identified weeds of sun and water. However, as part of your lawn care management, imagine how difficult this method will be when tackling extensive square feet of lawns.
  • Salt spray. This technique also best kills weeds through target applications. As a good weed killer, a salt spray keeps your St Augustine grass healthy while still tackling an identified pest problem. Salt as a natural drier dehydrates weeds, eventually killing them. A salt spray is applicable to different types of grass apart from the St August
  • Spreading corn gluten meal. Most uniquely, this homemade weed solution works best as a pre-emergent weed killer. Reasonably, don't wait to notice weeds starting to emerge in your new lawn to apply this home solution. Cornmeal works by drying out weeds at the seed level and creating a weed barrier over your lawn.

Other Tips For Maintaining Weed Free St Augustine Grass

Weed control measures for your St Augustine lawns also help tackle the pest problem that often plagues grasses. In addition to the mentioned types of herbicides and home lawn care solutions, there are other necessary lawn routines that help with weed and pest control in the long run.

Here are additional tips for caring for your St Augustine grass lawns:

  • Maintaining an excellent fertilizing and watering schedule. This routine care technique ensures that your St Augustine grass grows healthy to suffocate and kill weeds. Through adequate fertilizing and watering, you are guaranteed an instant green lawn.
  • Maintaining a longer lawn than usual. This method ensures that you obtain a vibrant lawn that kills weeds by overshadowing and blocking weeds from the sun.
  • Using all-year-round pest control management. Besides having effective methods that kill weeds, a healthy lawn is also achieved through effective pest control measures. You can find an active ingredient in solutions that kill weeds and pests, such as neem-oil products for easier management.
  • Grass aeration also increases the strength of your St Augustine grass roots. Aeration also improves the penetration of fertilizer into the soil.

Safety First And Always

At all times, when keeping your lawn weed-free using pre-emergent or post-emergent solutions, the safety of human beings, the environment and animals is paramount. Weed killers for St Augustine grass can irritate the skin and eyes. Moreover, chemical-based herbicides might be adverse to the nervous and respiratory systems. In extreme cases, St Augustine lawn herbicides can cause shock and death.

For your safety during lawn herbicide applications, we recommend wearing protective clothing for your entire body. Also, always ensure that kids stay away from spraying zones.

Considerably, applied St Augustine lawn weed killers should not be harmful to pets as well as wild animals that use the lawn. In addition, unless you are handling pest problems, St Augustine pest control and weed-killing solutions shouldn't harm animals and insects part of the lawn ecosystem, such as butterflies and bees.

How Do You Choose the Best Weed Killer for St Augustine Grass: (Buying Guide)

Things you have to consider before buying a weed killer for St Augustine grass: Several different varieties of this common lawn grass exist, each with its list of welfares. They also have some types and maintenance theory. For example, a St Augustine grass lawn needs at least four hours of sunshine every day. Ideally, a St Augustine grass lawn has more shade tolerance than others.

St. Augustine goes through a period of invisibility and turns brown in winter, but this thing quickly greens up once early spring, and warm temperatures attain. Now, it is known to us that weed is another mate of grasses because they grow up and destroy the beauty and force them to become less fertile. The best way to prevent this problem is by applying weed killers over the grass. That is why now we are going to discuss the best weed killer for St. Augustine grass.

You must know before you buy that not all medicines or killers are suitable for any weeds. On the other hand, your choice might vary according to the grass and land. For example, rocky areas may use a non-selective weed killer, while areas near waterways may require an organic lawn herbicide. As a result, you have to choose the most appropriate weed killer for your respective lawn. However, most of the time, a few basic things remain the same for the weed killers, which you must consider before you buy.

Here is a list of things that you must consider in your mind before choosing the best weed killer:

  • Herbicides will not kill your grass. It is essential to ensure that your selected product only prevents the weed, not doing any further damage to your grass. Choose a product that won’t kill your lawn grass.
  • You must know the type of weeds in your lawn. For better and safest use, it is crucial to know about the weed because then you will find the perfect and accurate killer for your grass.
  • You have to ensure the safety of kids and pets. In your lawn, these are things that will move around, so use organic and natural products for safety.
  • Different weeds grow in different states like flower beds. So, first, know about the place and weed type, then go for the killer.
  • Not all the products will cover the whole space that you need. You have to choose an appropriate weed killer based on the lawn area and space. Accordingly, the limitation of your select weed killers can only be practical, depending on their limits. So be sure about that. For large spaces, choose commercial killers that cover large spaces.
  • You have to know how long for weed killer to work.

Final Verdict

To sum up, the given list has seven quality products according to the need we have to kill or prevent the weed from our lawn. You can wisely choose your product by watching its features and advantages. Be aware of your need and choose wisely, because there are many products available in the market, but some are worthy.

Ian Mutuli

About the author

Ian Mutuli

Founder and Managing Editor of Archute. He is also a graduate architect from The University of Nairobi, Kenya.
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