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The Best Fertilizer For St Augustine Grass – A Complete Guide

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There are many options for your lawn’s turfgrass, and St Augustine grass has always been a forerunner with its capability to keep your lawn green. As lush as it can be, you need to prepare the best fertilizer for St Augustine grass to ensure that it doesn’t lose any vitality and growth rate.

To make things easier for you, we have prepared a concise and thorough buying guide at Growingherbsforbeginners.com. Let us walk you through our 6 tested picks and point you in the right direction.

Best Fertilizer For St Augustine Grass – Top 5

RTS Home Accents Rainwater BarrelScotts Southern Lawn Turf Builder
Good Ideas IMP-L50-SAN<br /> Pennington UltraGreen Starter Lawn Fertilizer
Good Ideas RW65-GRN Rain WizardScotts Turf Builder Southern Triple Action
Enviro World EWC-10 FreeGardenThe Scotts Lawn Repair EZ Patch Fertilizer
Enviro World EWC-10 FreeGardenSimple Lawn Solutions Maximum Green & Growth

#1. Scotts Southern Lawn Turf Builder – Best Overall


  • Brand: Scotts
  • Style: Standard
  • Application: Broadcast spreader/drop spreader
  • Weight: 28.3 pounds
  • Area: 10000 sq. feet
  • N-P-K ratio: All-in-one particles

The reason we believe that the Scotts Southern Lawn Turf Builder deserves the best overall spot lies in its special formula. This formula was specifically designed to protect all Southern grass types, including St Augustine grass, against drought and extreme heat.

Scotts Southern Lawn Turf Builder
The Scotts Southern Lawn Turf Builder is the best choice.

With its All-In-One particles tech, you can expect the nutrient distribution process to be even with each application. It’s because each particle shares the same N-P-K ratio, so every inch of your lawn can receive the same amount of nutrients. 

As a result, there is no excess component; no risk of burning is present, and the root system doesn’t overgrow. The overall health of the lawn is ensured for quite a while.

This All-In-One solution also makes the fertilizer more manageable during the spreading procedure. You will not need to spend too much time familiarizing yourself, saving lots of effort.

You can spread this excellent product over a huge area of 10000 square feet. This kind of covering capability is unmatchable by all other options available in this list. Despite this huge spread, you can expect the fertilizer to completely cover each leaf.

We do want to note that this fertilizer is not one that you can use on lawns in bad shape. Due to its potent nature, weakened lawns will not be able to handle the dosage and die out.


  • Arrived ready to use
  • Compatible with any season
  • Safe to touch right after application
  • Providing lots of nutrients
  • Especially good against warmer temperatures


  • Not good at restoring weakened lawns

#2. Pennington Ultra-Green Lawn Starter Fertilizer – Runner-Up


  • Brand: Pennington
  • Style: Standard
  • Application: Broadcast spreader
  • Weight: 14 pounds
  • Area: 5000 sq. feet
  • N-P-K ratio: 22-23-4

If you are struggling with your budget, the Pennington UltraGreen Lawn Starter Fertilizer is a godsend. Not only does it cost a lot less than the other options here, but it also provides quite a lot of value for its price. For example, it can cover a respectable 5000 sq. feet area.

Pennington UltraGreen Starter Lawn Fertilizer
The Pennington UltraGreen Lawn Starter Fertilizer offers much more than you realize.

It is especially good at starting new lawns through sods or seeds and overseeding an existing lawn. The reason for this strength lies in its capability to build deep and strong roots, thanks to a high phosphorus content (23). These roots are vital for a fast lawn establishment process.

We also love that this dry fertilizer includes a 5% iron content. As you may know, iron plays a major part in many vital functions. For example, chlorophyll production, Nitrogen fixing, and enzyme development all depend on iron.

It also has a certain level of flexibility, being compatible with all grass sod and seed types, not just St Augustine. That is why you won’t be forced to use it sparingly for only one purpose. This strength lets it plug into already established root systems fast.

You do need to watch the amount used with care. If it goes over a certain threshold, your grass will burn.


  • Making grass greener
  • Quick greening process
  • Making thick lawns


  • Easily burning the grass

#3. Scotts Turf Triple Action Southern Builder – Best For Pest And Weed Control


  • Brand: Scotts
  • Style: Standard
  • Application: Broadcast, drop, or hand-powered spreader
  • Weight: 26.6 pounds
  • Area: 8000 sq. feet
  • N-P-K ratio: 29-0-10

The Pennington UltraGreen Lawn Starter Fertilizer is a heavily specialized fertilizer, with the goal being complete pest and weed elimination. 

That is exactly why you see a unique 1.352% concentration of Atrazine, which eliminates weed by hindering the photosynthesis process. This method can take care of most lawn weeds, ranging from dollar-weed to plantain and henbit. 

Scotts Turf Builder Southern Triple Action
The Pennington UltraGreen Lawn Starter Fertilizer performs the best against pests.

It is also specifically good against red fire ants and worms, thanks to the 0.139% Bifenthrin. 

As Bifenthrin messes directly with insects’ nervous systems, you only need to apply this fertilizer and wait for a maximum of 3 hours for clear results. That’s not all; this effect can last for a long while, with the biggest reported period being 6 months.

This fertilizer uses a highly nutritious combination to ensure that the grass will survive against droughts and heatwaves. After all, not many fertilizers have a 29-0-10 N-P-K ratio, which both strengthens the grass’ water absorption and toughness.

There is something you need to keep in mind, though. The most vital one is the fact that it cannot work on Northern lawns due to its specialized nature for Southern grasses.


  • Quick result
  • Relatively easy to apply
  • High Nitrogen concentration
  • Good value with a 3-in-1 effect


  • Not compatible with Northern lawns
  • Sometimes clumping when it goes into the blender

#4. Scotts Lawn Repair EZ Patch Fertilizer – Best Lawn Repairment


  • Brand: Scotts
  • Style: Mulch
  • Application: Direct application
  • Weight: 3.75 pounds
  • Area: 85 sq. feet
  • N-P-K ratio: 2-0-0

Some options, while very good for healthy lawns, can turn into poison for weaker ones. This case requires something with some specialty like the Scotts Lawn Repair EZ Patch Fertilizer. When it comes to lawn restoration, nothing can beat it.

Scotts Lawn Repair EZ Patch Fertilizer
The Scotts Lawn Repair EZ Patch Fertilizer excels at lawn repair.

It is the only fertilizer on this list to combine mulch with fertilizer to increase its performance. As a result, you can fix bald patches on the lawn quickly. After all, mulch is capable of absorbing an amount of water measuring 6 times its size.

The mulch protection layer will also last for a long time, only disappearing if the environment moisture reaches a certain threshold. This protection extension means that the grass can grow faster as it doesn’t need to try to survive.

It does ask for some follow-ups, though. There is a need to consistently water the area after the application process finishes. People with less free time will struggle with this issue.


  • Only requiring 14 days to show results
  • Capable of growing your lawns’ patches 
  • No need for a huge spread


  • Not having grass seed prevents immediate plugging
  • Requiring consistent watering

#5. Simple Lawn Solutions Maximum Green & Growth NPK – Best Liquid


  • Brand: Simple Lawn Solutions
  • Style: Liquid
  • Application: Direct application
  • Weight: 2 pounds
  • Area: 3,200 sq. feet
  • N-P-K ratio: 28-0-0

If you are not content with the spreading process that standard fertilizers do, you can always check out the Simple Lawn Solutions Maximum Green & Growth NPK. As the only liquid option here, it is one of the easiest to apply.

The Simple Lawn Solutions Maximum Green & Growth
The Simple Lawn Solutions Maximum Green & Growth NPK is the best liquid option.

All you need to do is connect the container with a sprayer, and you are good to go. The whole container can cover a maximum area of 3200 square feet while attached to this sprayer. Its liquid nature also ensures an easier time for the grass to digest.

This best liquid fertilizer for St Augustine grass features a special 28-0-0 ratio. As a result, it excels at coloring the lawn in a lush green shade. The 28% Nitrogen content also makes it much more manageable to develop the lawn in a dense direction.

It is, however, not that friendly to pets. If your pets digest it mistakenly, there is a high risk of an upset stomach.


  • Good at cleaning up pet pee spots
  • Only need 1 to 2 applications
  • Compatible with many grass types
  • Long-lasting
  • Making the grass denser


  • May harm pets

Things To Consider To Get The Best Fertilizer For St Augustine Grass

N-P-K Ratio

There are 3 main ways that people use to label turf and lawn fertilizers, weight, amount, and the nutrients they provide. The last one is what we call the N-P-K ratio.

A high Nitrogen content (N) makes it possible for the grass to develop faster and brings its color out. The phosphorus (P) concentration decides seed and bud formation, while potassium (K) takes care of the plant’s health.

All of these three components are vital for the growth of St Augustine grass. However, the most necessary one is, without any doubt, Nitrogen.

The reason for this necessity stems from the high concentration of Nitrogen present in St Augustine grass. That is why you will typically find a much higher Nitrogen percentage in turf fertilizers. For example, the most seen formula for this type of fertilizer is 15-1-5.

Liquid vs. Granular vs. Water-Soluble

There are 3 main forms that you can find: lawn fertilizers granular, water-soluble, and liquid. So, what kind of fertilizer is best for St Augustine grass? No option is the clear superior choice, as it all depends on your personal preference.


A large number of groundskeepers and growers tend to apply lawn fertilizer in liquid form to provide a fast growth boost. The reason lies in the liquid’s quick absorbance through the grass’s blades. As such, this form of fertilizer can work immediately, hence the name – fast-release fertilizers.

You can expect results in the span of only 3 or 4 days after applying it to your St Augustine grass species. This type of fertilizer is purchasable either at its full potency or in a diluted form. The usual method to apply it is through a garden sprayer pump.

Liquid fertilizers pass through the lawn just as fast as they go in. That is why you may need to reapply a lot more times than something like granular fertilizer.

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Looking no different from tiny grants, a granular form fertilizer has almost the same nutrient composition as liquid fertilizers. 

There is a slight difference in the release speed, with granular fertilizers being on the slower side. As a result, the roots of the St Augustine grass can come into contact with the nutrients for a long time.

You should not expect the same quick green transformation as liquid fertilizers. In exchange, there is no need for frequent application. The main way to apply granular fertilizer is through a spreader. Most of the time, slow-release Nitrogen fertilizer will take this form.


Despite its comparable appearance to granular fertilizers, this type of fertilizer cannot be applied using spreaders. You must instead use hose-end dispensers connecting to garden hoses. In this setup, water flowing through your dispenser will dissolve the granules and dilute them. 

You then disperse the result through hand-held sprayers, providing the same quick results as liquid fertilizers.

Organic vs. Synthetic

Organic Fertilizer

Natural fertilizers usually have the same nutrient composition as their synthetic counterparts. Still, they originated from all-natural sources like composted manure or earthworm castings. 

That is why you will see that they have a higher price tag, as gathering all the natural ingredients is a lot more costly. In return, you get an eco-friendly option that will not pollute your waterways or harm any aquatic life.


The main components of this fertilizer type are chemicals produced in a lab mimicking natural nutrients. Some options do have essential minerals present in healthy soils like boron, magnesium, and calcium.

Lawns tend to react to synthetic fertilizers the same way as organic ones. However, their high Nitrogen content means that your waterways will get polluted if they get out of the lawn.


Knowing when to use fertilizers is equally vital as what fertilizer to use. The best time to fertilize St Augustine grass is in spring, after the grass has turned into a complete green color. Fertilizing any sooner will surely damage your grass.

Our recommendation is to apply some all-purpose fertilizers with a high Nitrogen composition. Then, fertilize again every 6 weeks.

It’s hard for St Augustine grass to grow from seed, so the normal method is propagating with buds or sods. If you follow this method, remember to put in fertilizer with a balanced nutrient ratio of 10-10-10. Doing so boosts the plant’s health.

After this fertilizer has been digested completely, it calls for a high-Nitrogen one. Stop the fertilization process once the temperature drops when fall comes.

Lawn Size

A major aspect that many newcomers tend to overlook is considering the lawn size. You must make sure that the fertilizer can cover the whole yard. Also, you will need to reapply, so running out of fertilizer mid-season is not ideal.

Most granular form fertilizer packages can treat a minimum of 1000 square feet. Yet, any seasoned veteran knows that this is not nearly enough. If you have a large lawn, you are looking at upward of 10000 square feet to cover.


How To Make St Augustine Grass Thicker?

It is important to make sure that your grass is healthy for dense growth. You should fertilize the turfgrass well over spring and summer with high Nitrogen fertilizers. This way, the root receives a more nutritional haven to thrive for faster growth.

Do not use too many herbicides or pesticides, and keep the soil’s pH level in the 5 to 8.5 range. Otherwise, you won’t get any healthy root development.

Why Is My St Augustine Grass Turning Yellow?

The most common culprit is a lack of nutrients, as turfgrass needs a lot of nutrients. If it cannot have enough, it will fade.

Slow-release Nitrogen fertilizers will perform the best in this step due to their guaranteed seepage of nutrients and feeding between each application. After a while, the amounts of Nitrogen released will reach the peak value for the soil types.

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Is Epsom Salt Good For St Augustine Grass?

Epsom salt not only improves your soil’s nutrients but also serves as a sort of natural and ideal fertilizer without harming your lush lawns.

It is among the organic ingredients capable of providing Nitrogen, sulfates, and iron, all vital nutrients for your St. Augustine grass.

When Should I Fertilize My St Augustine Grass?

The answer depends on the location you are at and its inherent weather system. Of course, there is still a basic guideline.

Start the first process at most 2 weeks after you see the final frost when the grass turns green. This signifies the grass has broken its dormancy and is in need of extra support.


For all turf enthusiasts, having the best fertilizer for St Augustine grass is always the wise choice. Doing so will reward you with a dense and robust lawn capable of withstanding many temperature ranges.

If there is no specific requirement like treating iron deficiencies or rapid growth, then the Scotts Southern Lawn Turf Builder is the clear champion. This balanced fertilizer does a bang-up job at enriching the soil sample with essential nutrients. It also doesn’t carry any risk. 

It does still require some human intervention to get healthy growth for your green lawn, though. That is why simple fertilizer application will never be enough. You must also know which time is good to do so by reading through our buying guide and FAQs section.

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