The Best Fertilizer for St. Augustine Grass in 2024

St. Augustine grass (Stenotaphrum secundatum) is a spreading grass with a coarse texture. It is grown primarily in the southern United States. It is the least cold hardy of the warm season grasses, so it doesn’t grow in the northern United States. St. Augustine grass is a heavy feeder and requires a yearly fertilization program to look its best. 

Here are my picks for the best fertilizers for St. Augustine grass.

Best St. Augustine Grass Fertilizers

1. Milorganite 32 lb. Slow-Release Nitrogen – Best Eco-Friendly Fertilizer

Milorganite 32 lb. Slow-Release Nitrogen

Milorganite 32 lb. Slow-Release Nitrogen Fertilizer is my pick for the best eco-friendly fertilizer.

Milorganite has used biosolids left over from the wastewater treatment process for the nutrient source since 1926. The solids first came from the city of Milwaukee, Michigan.  

Milorganite 6-4-0 Slow-Release Nitrogen Fertilizer gives a pretty big bang for your buck because it contains slow-release nitrogen. Instead of fertilizing every two months, you only have to fertilize every four months. One bag every four months is fairly economical.  

The NPK ratio is 6-4-0, so it doesn’t have potassium in it. In addition, this fertilizer contains iron in a non-staining formulation and calcium. Using this product will make your lawn a deep green and help it develop strong roots.

The iron and calcium help the plant take up the other nutrients even in a higher pH lawn. Normally, lawns can suffer from iron chlorosis if the pH is high.

This bag of fertilizer covers 2500 square feet of lawn. It costs more than all but the Espoma fertilizer discussed below. However, since the bag will treat one large lawn or two small ones, it is still fairly economical.

Note that some states will not allow you to use a lawn fertilizer with phosphorus in it, so this product will not be legal in those states. 

To use Milorganite 32 lb. Slow-Release Nitrogen Fertilizer, mow your lawn and allow the clippings to remain on the lawn. Using half the recommended fertilizer, walk with your spreader from North to South. Using the rest of the fertilizer, walk with your spreader from East to West.

The fertilizer bag has a table with the correct spreader settings on it for several models of spreader. Sweep any spilled fertilizer up and spread it on the lawn. Wash your hands after handling this fertilizer. You do not need to water the fertilizer in after spreading. 

I think this is a good, economical fertilizer. I have a lot of phosphorus in my soil, so I cannot use this fertilizer on my lawn. I also hesitate to spread sewage solids on my lawn.

I would recommend this fertilizer if you do not have the money for a more premium fertilizer. Milorganite has two lawn fertilizers with very similar packages. This product is not organic because it contains sewage solids, which you cannot use in organic gardening.

Because this product is slow-release, you will not have to worry about burning your lawn if you apply it at the rate on the label. The fertilizer starts showing results about two weeks after application. 


  • Economical
  • Eco-friendly
  • Builds lush lawns
  • Does not contain potassium
  • Has non-staining iron and calcium


  • Uses sewage solids as the nutrient source
  • Not organic
  • Contains phosphorus, so can’t be used in some states or in areas with high-phosphorous soils

2. Scotts Turf Builder Southern Lawn Food – Best Turf Builder Fertilizer

Scotts Turf Builder Southern Lawn Food

Scotts Turf Builder Southern Lawn Food is my pick for the best turf-builder fertilizer.

This product is developed specifically for use on Southern lawns. It has an NPK ratio of 34-0-10 and includes four percent sulfur and two percent iron.

The nitrogen in Scotts Turf Builder will thicken and green up your lawn quickly. The potassium works to develop strong roots and a vigorous plant. The deep roots are more likely to stand up to the heat and drought we are famous for in the South.

The sulfur and iron will help prevent iron chlorosis, which turns plants yellow.

Unlike most lawn fertilizers, each particle of Scotts Turf Builder has all of the nutrients in the fertilizer. This makes getting an even distribution of nutrients much easier. A lawn treated with Scotts Turf Builder absorbs more water and nutrients than an untreated lawn.

This fertilizer is safe for kids and pets. It is okay to enter the lawn right after spreading the fertilizer on it. 

Scotts has a reputation for a big research and development department and for producing good products. They started over 150 years ago as a grass seed company but now make everything you need to plant and grow great grass. 

Scotts Turf Builder will burn your lawn if you apply more than the label says. While the fertilizer has a lot of slow-release fertilizer in it, you have to apply it every six weeks, which is more frequent than most slow-release fertilizers.

One package of Scotts Turf Builder will treat 5,000 square feet of lawn. It is moderately priced but will treat a large lawn twice or a small one five times. However, since you have to apply it every six weeks, this fertilizer is one of the more expensive fertilizers. 

To apply Scotts Turf Builder, mow the lawn and leave the clippings on the lawn. Set your spreader and spread half the fertilizer while walking North to South, and the other half when walking East and West. You do not need to water this fertilizer in.

Scotts only gives fertilizer spreader settings for its own spreaders, so if you have another brand of spreader you will have to figure out what setting to put it on based on the application rate. 

I think Scotts Turf Builder is a good premium fertilizer for St. Augustine grass. As mentioned, the fertilizer has a lot of research and testing behind it.

Because the fertilizer does not have phosphorus in it, you can use it everywhere you can grow St. Augustine grass.

I have a lot of potassium in my soil so I would choose another fertilizer, but if your soil is not high in potassium, this would be a good choice.


  • From a respected company
  • No phosphorus in fertilizer
  • Has iron and sulfur to prevent iron chlorosis


  • Pricey
  • Frequent application necessary

3. Espoma EOFW30 Organic Fall Fertilizer – Best Fall Fertilizer

Espoma EOFW30 Organic Fall Fertilizer

Espoma EOFW30 Organic Fall Fertilizer is my pick for the best fall fertilizer for St. Augustine grass. For more information on fall lawn fertilizers, be sure to check out my comprehensive article that covers everything you need to know about choosing the right fertilizer for your fall lawn.

In the fall, you need to apply a fertilizer with more potassium to help the lawn get through the winter and wake up in the spring.

This fertilizer has an NPK ratio of 8-0-5 with one percent calcium and one percent iron in it.

The nitrogen is mostly slow-release to feed the lawn through the fall and give it the energy to wake up in the spring. A slow-release fertilizer will not burn your lawn if it is applied at the recommended rate.

The potassium helps the lawn recover from the heat and drought stress of summer. In addition, it keeps the roots and plants strong and vigorous to survive the winter.

The calcium and iron prevent problems from nutrient deficiencies like iron chlorosis.

This product is safe for both established lawns and newly seeded, plugged, or sodded lawns.

The package feeds up to 5,000 square feet. The fertilizer is certified organic. This fertilizer is the most expensive fertilizer I have recommended.

Espoma has been a leader in organic lawn products since 1929. It is still owned by the fourth generation of the family that founded it. Espoma is a reputable company, and you can trust their products. I use a lot of Espoma products on my plants.  

To fertilize your lawn with this fertilizer, mow the lawn and leave the clippings on the lawn. Apply the fertilizer to a dry lawn at the rate of six pounds per 1,000 square feet, or 5,000 square feet per bag. If you do not routinely leave your clippings on your lawn, apply the fertilizer at a rate of twelve pounds per 1,000 square feet, or 2,500 square feet per bag.

There is a table of spreader settings for you on the bag, so you do not have to figure them out on your own. Water within 24 hours of spreading the fertilizer, preferably right after spreading it.

Don’t apply the fertilizer before a big rain or your expensive fertilizer will go down the storm drain, where it causes problems in creeks and rivers. 

I like Espoma, as I mentioned above. I can’t use this product because of the high potassium level in my soil, but I would use it if I could. It is a little pricey, but good organic products cost more than synthetic products.

Organic products are more eco-friendly because they do not rely on petroleum products for their nutrients. Since you only have to apply it once a year, and one bag will cover most lawns, I think the extra cost is worth the money.

Espoma also has other organic products for the lawn that are applied at other times of the year, but they are beyond the scope of this article. 


  • Organic
  • Phosphorus free
  • Premium product
  • Once a year application
  • Eco-friendly


  • Pricey

4. Simple Lawn Solutions Extreme Grass Growth Lawn Booster – Best Liquid Fertilizer

Simple Lawn Solutions Extreme Grass Growth Lawn Booster

Simple Lawn Solutions Extreme Grass Growth Lawn Booster is my pick for the best liquid fertilizer for St. Augustine grass.

The NPK ratio is 6-18-0. The nitrogen helps green up the lawn and makes it grow vigorously. The phosphorus makes the roots grow deep, which helps the lawn resist drought and heat. It is essential for grass to become established after being planted.

This fertilizer also contains humic acid, which helps the microbes in the soil break down nutrients into forms the plants can use. It also enhances seed germination.

The humic acid is from Leonardite, considered the highest quality humic source, and is extracted with a proprietary process that leaves it very pure. Simply Lawn Solutions uses high-quality, feed-grade ingredients. 

Simple Lawn Solutions Extreme Grass Growth Lawn Booster is great for new and established lawns. It increases vertical and horizontal growth to form a thick, luscious lawn.

It is made by a family-owned business with 25 years of commercial lawn management experience. They make Simple Lawn Solutions Extreme Grass Growth Lawn Booster in the United States.

This product is safe for kids and pets. This product cannot be used in states that have laws against applying phosphorus to lawns. It is not organic. The formula is slow-release, so you can go longer before you need to reapply it. However, if it rains hard soon after you apply it, the fertilizer will leach out of the soil. 

Simple Lawn Solutions Extreme Grass Growth Lawn Booster is easy to use. Simply put the container on the end of your hose, turn on the hose, and spray your yard.

Water the lawn for twenty minutes within twenty-four hours of spraying your lawn with this fertilizer. The container covers up to 3,200 square feet. It is moderately priced. You should notice the results in about ten days.  

I would use this product when establishing a new lawn, for the first fertilization of the year, and to repair a damaged lawn. I would not use it after that because the high phosphorus content can cause problems. A buildup of phosphorus makes it hard for the lawn to absorb some nutrients and inhibits the lawn’s growth.

If you are somewhere with lots of phosphorus in your soil, this would not be a good product to choose. I would use straight nitrogen instead. This product does not have potassium, so if your soil does not supply that, you should choose another product.

I live in a high phosphorus, high potassium area so I don’t have to worry about adding either of those nutrients. This product also doesn’t have any of the other nutrients lawns need, such as iron. 


  • Easy to use
  • Covers 3,200 square feet
  • Safe for kids and pets
  • Enhances seed germination


  • No potassium
  • Contains phosphorus so can’t be used in some states
  • Not organic
  • Better options for established lawns

5. Pennington 100536576 UltraGreen Lawn Fertilizer – Best Overall Fertilizer

Pennington 100536576 UltraGreen Lawn Fertilizer

Pennington 100536576 UltraGreen Lawn Fertilizer is my pick for the best overall fertilizer.

This granular fertilizer can be spread with a spreader or drop fertilizer. The fourteen-pound package covers 5,000 square feet and is the least expensive fertilizer I have recommended. That doesn’t mean it is cheap, just inexpensive. The NPK ratio is 34-0-4 with iron.

Part of the nitrogen is fast acting while part of it is slow-release, so your lawn greens up fast but you don’t have to reapply the fertilizer for three months. The fertilizer will create a deep, lush lawn with good roots, making it heat and drought resistant.

Pennington UltraGreen Lawn Fertilizer can be used everywhere because it does not contain phosphorus. However, if you have soils deficient in phosphorus, this isn’t the product for you. This product is not organic. This product is primarily for established lawns. 

Pennington was founded by Brooks Pennington, Sr. In 1945. It started as a small seed company in Madison, Georgia, and has expanded throughout the United States. Its newest facility is in Oregon. For the last 70 years, Pennington has developed and sold fertilizer and grass seeds. For the last 60 years, it has also developed and sold wild bird food seeds. The newest products on the shelf are seeds for food plots to attract wildlife, primarily deer, turkey, and quail. Pennington backs their products with a money-back guarantee.  

Pennington UltraGreen Lawn Fertilizer can be used on a wet or dry lawn. I would recommend spreading it on a dry lawn. If you spread it on a wet lawn, the particles on a wet lawn, they may stick to the grass blades and burn them.

Set the spreader according to the chart on the bag. Use half the fertilizer and spread from North to South, then use the other half to spread West to East. Be careful not to exceed the recommended amount of fertilizer because it will burn your lawn.

You will also need to water the lawn well after spreading the fertilizer. This helps the fertilizer dissolve so the lawn can use the nutrients in it and helps prevent fertilizer burn. You should see a difference in your lawn in two weeks. 

I think this is a good overall fertilizer. It is affordably priced and only has to be spread every three months. The bag is self-sealing, so you don’t have to waste any fertilizer that is left over, and it won’t go stale in the air.

The package also protects against moisture getting in the fertilizer, although I would not store the bag where it could get rained on. Even with the self-sealing bag, I recommend using all your fertilizer before fall. Fertilizer degrades as it ages and even the best brands are not good after a year. 


  • Reasonably priced
  • Self-sealing bag
  • Only apply every three months
  • Money-back guarantee
  • No phosphorus


  • Not organic
  • Can burn lawn
  • Uses a lot of water

How I Use These Fertilizers?

I would use Pennington’s fertilizer in early spring and every three months after that until September.

I would then spread Espoma EOFW30 Organic Fall Fertilizer in October to prepare my lawn for winter.

If I were putting in a new lawn, I would use Simple Lawn Solutions Extreme Grass Growth Lawn Booster- Liquid Spray Concentrated Starter Fertilizer with Humic Acid.

As I have mentioned, my soil is high in phosphorus and potassium. However, I would use Scotts Turf Builder Southern Lawn Food if that were not true, and my lawn was damaged or sparse.

Finally, if I wanted a very affordable, eco-friendly option, I would use the Milorganite 32 lb. Slow-Release Nitrogen Fertilizer.

Soil Tests

As you can see, it is important to know if your soil has a lot of phosphorus and potassium in it. The best way to do that is to do a soil test every two to three years.

This test takes a sample of your lawn’s soil and tests it for nitrogen, phosphorus, and potassium. You can also pay for a test that includes the other nutrients plants need.

All the tests show soil pH, which is important for nutrient availability. You can get instructions for a soil test from your county Extension agent or search for your state’s soil lab and get instructions on their website. 

Types of Fertilizer

Fertilizer comes in several forms. Here is an explanation of the most common ones. 

Liquid Fertilizer

Liquid fertilizer is sprayed on the lawns. It may be ready to use or have to be mixed. Many ready-to-use fertilizers can be hooked up to your garden hose without having to put them in your lawn sprayer.

Concentrates cost more initially but cost less per application. You do need an inexpensive hose-end sprayer to use them. The nutrients in liquid fertilizer are usually released fast but may have some slow-release fertilizer in it. 

Water-Soluble Fertilizer

Water-soluble fertilizer is a solid that dissolves completely in water. It is usually mixed with water and then used just like a liquid fertilizer. 

Granular Fertilizer

Granular fertilizer looks like small rocks. It is spread using a push spreader or hand spreader.

Most fertilizer bags have a chart containing the spreader settings for different brands of spreaders. Scott bags only have the settings for Scott spreaders, so you have to figure out where to set your spreader if you have another brand.

Most granular fertilizer is slow-release but some contain some fast-release fertilizer that works immediately. 

Organic Fertilizer

Organic fertilizers feed soil microbes which break down soil nutrients into forms plants can use. Synthetic fertilizers feed the plants directly and not the soil microbes. Repeated use of synthetic fertilizers can cause the soil microbes to starve in a garden.

In addition, organic fertilizers use substances found in nature. They are certified by an agency, usually the United States Department of Agriculture or Oregan Tilth in the United States, as only containing substances from a list of approved organic ingredients. Synthetic fertilizers are usually made from petroleum products or a mix of organic and synthetic ingredients.  

Slow-Release Fertilizer

Slow-release fertilizer granules are coated with a coating that breaks down slowly over time, letting the nutrients trickle out into the soil. The coating usually takes a week to two weeks to start breaking down, so results are slower than with a liquid fertilizer, but you do not have to reapply slow-release fertilizer as often as liquid fertilizer. 

Weed and Feed Cautions

Be very careful using a weed and feed product on St. Augustine grass. Many weed and feed products contain 2,4, D, a chemical that kills broadleaf plants. However, St. Augustine grass is a broadleaf plant.

I have observed these weed and feed products completely kill a St. Augustine grass lawn. Make sure any weed and feed product you use explicitly says it is safe for St. Augustine grass lawns or you will kill your grass as well as your weeds. 

How Do I Choose St. Augustine Grass Fertilizer? 

To some extent, choosing a fertilizer for your St. Augustine grass is a personal choice. Here are some factors to consider. 


Do you own a spreader? Do you prefer to handle a liquid or a solid? Some people hate walking back and forth on their lawn spreading a granular fertilizer. They prefer using a liquid.

On the other hand, most granular fertilizers have at least half of the nutrients in a slow-release form, so you do not have to reapply them as soon. If your lawn needs help today, liquids tend to work faster than granules.

You need to balance out the pros and cons of each form of fertilizer for you and your lawn when choosing a fertilizer to apply. 


Some people do not have a lot of money for fertilizer, so they choose a cheaper fertilizer out of necessity. However, cheap fertilizers do not have as high a quality ingredients as premium fertilizers.

In addition, premium fertilizer ingredients tend to be more bioavailable than cheaper fertilizers, so you need to use less or apply it less often.

I find it wise to get the best fertilizer you can afford because you will be happier with the results.


Fertilizers have different ratios of nutrients. The ideal ratio for St. Augustine grass is 3-1-2. In places with laws that prohibit applying phosphorus to lawns, that becomes 3-0-2.

Most lawn fertilizers are multiples of these ratios or close to that, for example, 15-5-10 or 30-0-15. Choosing ratios that have a large percentage of nitrogen and a low or zero percentage of phosphorus and a lower percentage of potassium works best for this kind of lawn.

The last fertilization of the year should have more potassium than usual to help the lawn through the winter. 

I use a combination of these three factors to choose my fertilizers regardless of what plants I am fertilizing. I believe that is the most successful way to choose from the many, many different types of fertilizer in stores without getting overwhelmed or confused by the choices. 

Why Should You Fertilize St. Augustine Grass?

St. Augustine grass is a heavy feeder that needs more nutrients than it can obtain from the soil. If you do not fertilize it, the grass will be thin and not grow well. 

When Do I Fertilize St. Augustine Grass?

I start fertilizing St. Augustine grass three weeks after it turns green and then every eight weeks, or the interval on the label, after that until the fall. I stop fertilizing my St. Augustine grass four to six weeks before the first frost date in my area. In areas where it never gets cold enough to force grass into dormancy, fertilize all year. 

How Do I Fertilize St. Augustine Grass?

There are two ways you can fertilize your St. Augustine grass. You can use a hose-end sprayer or a spreader. 

Hose-End Sprayers

Many liquids come in packages that just screw into your hose. Turn on the hose and spray the lawn. Other products have to be mixed by adding an appropriate amount to a hose-end sprayer you own, then turning on the hose and spraying it. Make sure to completely cover the whole lawn so all of it is wet after spraying. 


The other way to spread fertilizer for lawns is a spreader. These come in walk-behind models and handheld models. Most fertilizer sacks have a list of different model spreaders and the correct settings to place the spreader on to release the right amount of fertilizer.

When using a spreader, slightly overlap the stripes you walk back and forth so you do not miss some grass and have a light stripe on your lawn. I also spread one-half of the fertilizer walking from North to South and back and the other half of the fertilizer walking from West to East and back to make sure I get enough on the lawn and don’t miss any part of it. 

How Often Do I Fertilize St. Augustine Grass?

The frequency of fertilization depends on the product. Granular fertilizer is usually used once every eight weeks. Fertilizers with slow-release formulations may only need to be applied every three months. Liquid fertilizers are usually used more frequently, such as monthly. Depending on your soil and the fertilizer you use, you may need to fertilize with iron in between regular fertilizations. 

Final Verdict

My pick for the best overall fertilizer is Pennington UltraGreen Lawn Fertilizer. It is widely available and does a good job of greening up St. Augustine grass. In addition, it is reasonably priced.

My pick for the best fertilizer to winterize your lawn is Espoma EOFW30 Organic Fall Fertilizer. I like the company and St. Augustine grass needs a dose of nitrogen and potassium to prepare for winter and early spring.

My pick for the best liquid fertilizer is Simple Lawn Solutions Extreme Grass Growth Lawn Booster- Liquid Spray Concentrated Starter Fertilizer with Humic Acid. It is especially good for establishing a new St. Augustine grass lawn.

My pick for the best turf builder fertilizer is Scotts Turf Builder Southern Lawn Food. Scotts’ products are dependable and easy to find.

My pick for the most eco-friendly fertilizer is Milorganite 32 lb. Slow-Release Nitrogen Fertilizer. The nutrients in this fertilizer come from the solids left after wastewater is treated. It is also fairly economical. Everyone wants a thick, lush, green St. Augustine grass lawn and these products will help you get that.

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Stephanie Suesan Smith

Stephanie Suesan Smith has a Ph.D. in psychology that she mainly uses to train her dog. She has been a freelance writer since 1991. She has been writing for the web since 2010. Dr. Smith has been a master gardener since 2001 and writes extensively on gardening. She has advanced training in vegetables and entomology but learned to garden from her father. You can see her writing samples at, and her vegetable blog at

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