The 6 Best Fertilizers for St. Augustine Grass in 2023

As a homeowner with a lawn and garden, you know that proper fertilization is key to keeping your plants healthy. Different fertilizers work better in different parts of the country, and even within a single state, the best fertilizer for your lawn may vary depending on the climate and soil type.

Different types of plants require different types of fertilizer as well, so it can be tricky to know which ones are best for you if you have a lawn of St. Augustine Grass. One of the best ways to ensure your lawn stays lush and thriving is by using a fertilizer specifically designed for this type of grass.

There is no one-size-fits-all answer to the question of which fertilizer is best for St. Augustine grass. However, we’ve created a list of six different fertilizers that are known to be effective for St. Augustine grass lawns nationwide. In this blog post, we’ll take a look at each of these six fertilizers, as well as discuss how fertilizers work and provide tips on how to choose the right one for your yard. So whether you’re just getting started with lawn care or you’re looking for an upgrade, read on for the best tips and advice!

What is St. Augustine Grass?

St. Augustine Grass, also called Buffalo Turf, Buffalo Grass, and Stenotaphrum Secundatum, is a warm season grass that is popular in tropical and sub-tropical climates, such as in the southern United States. Although it can be found in many states, it grows best in humid climates with hot summers.

It does well in full sun and can be used for lawns, golf courses, and parks. It can often be seen in lagoons and marshes, along shorelines, and other places with a high degree of moisture.

It forms a thick, carpet-like lawn of sod that can be useful in crowding out other grasses and weeds. It is a medium-maintenance to high-maintenance turf grass.

What Does It Look Like?

The blades are a dark green color, and it will grow taller than most other types of grass. It has flat blades that are often fairly wide. It spreads by above ground stolons, often referred to as runners, and often forms a thick and dense carpet layer of grass right above the soil.

A healthy lawn should be thick, with a deep green color. If your St. Augustine Grass is yellowing, browning, or has dead patches, you may need to fertilize it.

What is Fertilizer?

Fertilizer is a substance that you put into the soil or plant tissue to give nutrients to the plants. It may be manufactured from natural or synthetic materials. There are numerous distinct types of fertilizer, and they’re utilized in a number of applications. The most beneficial fertilizers will assist your lawn and garden in obtaining the minerals they need to develop healthy plants.

In the past, fertilizer consisted almost entirely of organic ingredients such as human and animal manure, compost, mined minerals, and agricultural rotations. Synthetic fertilizers have become popular in the last several centuries, and fertilizers that contain nitrogen, phosphorus, and potassium are the most common.

How Does It Work In My Lawn?

Fertilizers work by encouraging the growth of plants, which they can do in two ways. The first method is to supply the plants with nutrients they require and can utilize to develop.

Fertilizers primarily contain nitrogen, phosphorus, and potassium. Each of these three macronutrients, as they are called, have a specific purpose.

  • Nitrogen: promotes leaf growth
  • Phosphorus: aids in developing the roots, flowers, seeds, and fruit
  • Potassium: helps stem growth, flowering, and fruiting, and promotes the movement of water within the plant

Calcium, magnesium, and sulfur are the three most common secondary macronutrients, and there are many micronutrients such as copper, iron, manganese, zinc, and boron.

Some fertilizers may improve the soil’s capacity to retain water and support aeration by increasing soil moisture retention and enhancing aeration. However, this isn’t very typical, and it’s not significant in comparison to the nutrients supplied by fertilizers.

Different Fertilizer Options

There are multiple types of garden fertilizers. The two main kinds you would see being sold are granule fertilizers, and liquid fertilizers.

Both of these types of fertilizer can come as organic or inorganic. They also can vary with regards to the strength of their N-P-K ratios and levels.

Liquid vs. Granular Fertilizer

Granular fertilizer comes sold as very small granules that you can spread around your lawn. Granular fertilizers must be applied and mixed into the dirt by hand, but they have a longer lifespan than liquid types that require reapplication every few weeks. You can mix these granules into the soil or do what’s called ‘top dressing’. Top dressing basically entails sprinkling the particles on the root zone of the plant.

Slow-release or quick-release are the two types of granular fertilizer available. Slow-release granular fertilizers, often given as monthly applications, release nutrients gradually over time. Quick-release granular fertilizers, given instead as weekly applications, are designed to deliver nutrients more quickly but in smaller amounts.

Liquid fertilizers, on the other hand, are made up of dry granules and liquid concentrates that must be combined. You apply this type of fertilizer by spraying the roots of seedlings or other vegetation and plants. Over-watering seeds can cause them to wilt and die. Watering the roots is often ineffective, while liquid fertilizer applied directly to plant leaves in many situations may be more successful. Liquid fertilizer tends to be quick-release.

Water-soluble fertilizers are often diluted with water before being applied to soil, so as to avoid causing potentially damaging runoff when not utilized appropriately.

Organic vs. Synthetic

In any case, no matter what kind of fertilizer you use, it will either be inorganic or organic fertilizer. The two subsets of fertilizer differ in two ways: they use different components and the nutrients are delivered to the plants via different methods.

Inorganic or synthesized fertilizers are created from nitrogen, phosphorus, and potassium compounds generated by industrial processes. These are fertilizers that contain primarily one or more of nitrogen, phosphorus, and potassium in large percentages. These fertilizers are highly concentrated and targeted at the plants’ specific requirements rather than being diluted. Although, the majority of them also contain minerals obtained from naturally occurring mineral deposits.

Examples of organic fertilizers – those which come primarily from animal and plant sources – are compost, different types of manure, and different ‘meals’ – blood meal, alfalfa meal, cottonseed meal, kelp meal, and bone meal. These fertilizers include a lower amount of NPK macronutrients, but they do provide vital organic matter to the soil, which helps to improve moisture movement and work in tandem with living microorganisms in the soil to nourish plants.

NPK Ratio

The nitrogen-phosphorus-potassium (N-P-K) ratios are one of the most crucial elements to consider when purchasing fertilizer since these are needed for plant development. The goal should be to discover a ratio that is comparable to what your plant needs based on its species type’s requirements.

Fertilizer products typically list their NPK levels in a ratio format, such as 10-10-10 or 4-3-4. The number list is always arranged in the order N-P-K, so 12-4-8 means 12% nitrogen, 4% phosphorus, and 8% potassium.

It’s typically ideal to do a soil test before applying fertilizer to determine your garden soil’s natural fertility. The information will reveal which elements your soil may need, so you can feed it with fertilizer.

As mentioned above, the most important component required for plant growth is nitrogen, phosphorus is essential for the development of roots, flowers, seeds, and fruit, and potassium aids in the formation and growth of stems and roots, and the movement of water within grass and plants.

When to Fertilize

You must be precise with the timing of fertilizing in order for your lawn to thrive. But, when do you actually need to apply fertilizer? At what time of day do you apply it? How often, and at what time of year? These are all valid concerns.


St. Augustine Grass prefers a temperature range of 60 to 65 degrees Fahrenheit, or above. This is around early spring in the climates that it is found in, so start to fertilize around then – middle of March to early April. The danger of frost has passed, and the grass is halfway green.

You also might want to fertilize once more at the end of spring. This is approximately two or three months following the initial springtime fertilization – roughly, early June or late May.

You should again apply fertilizer around early to late September, at the end of the summer season and the start of fall. You should make sure this is a slow-release fertilizer with a higher nitrogen content than phosphorus and potassium in the NPK ratio.

You don’t need to fertilize St. Augustine Grass in the winter months.


So, how often should you fertilize your grass? Is it possible to over-fertilize St. Augustine Grass? Yes, it certainly is. Excessive nitrogen application can harm your grass, even if it’s a lawn that is fed with fertilizer. However, many fast-acting fertilizers lose their power quickly and can be used as frequently as weekly. Also, fertilizing more often is less harmful to the grass than using too large a dose fertilizer at one time. Follow the directions on the label for a concentrate’s dilution, and fertilize as often as suggested. 

Why To Use Fertilizer

It’s critical to pick the appropriate fertilizer for your lawn. It will have an impact on the health, look, and fullness of your grass as well as its ability to combat weeds and diseases.

A well-fertilized lawn will grow thick, tall, and a dark green. The healthier and thicker a lawn is, the less chance of weeds being able to grow, or for disease or rot to set in. The soil will flourish and absorb nutrition and water better, so you don’t have to water as often or use as much fertilizer supplement. Plus, it will look great.

The best fertilizer to use for St. Augustine Grass is that which can provide approximately 1 pound of nitrogen for every 1,000 square feet of lawn. The nitrogen helps the St. Augustine grass develop a dark green color and grow to its full thickness.

Top 6 Fertilizers To Use On St. Augustine Grass

#1. Andersons Professional PGF Complete 16-4-8 Fertilizer with Humic DG

The Andersons Professional PGF Complete 16-4-8 Fertilizer with 7% Humic DG 5,000 sq ft
  • Phosphorus-free fertilizer blend with fine particle size that includes humic acid, which helps increase turf quality and reduce nutrient requirements
  • Contains MUtech coated slow release nitrogen to provide uniform growth and extended feeding
  • DG particles do not rely on a physical coating to release nutrients. Coated fertilizers (used by our competitors) are very susceptible to damage from mowers, resulting in premature nutrient release.
  • Small particle size gives you twice the number of particles per square foot. DG particle disperse quickly and completely when watered, moving directly into the soil.
  • Not for sale in California or Oregon

The Andersons Professional PGF Complete 16-4-8 Fertilizer with Humic DG is the best overall fertilizer for use on St. Augustine Grass. The high level of nitrogen in the NPK ratio is great for the grass to grow full, green, and healthy. It also contains other micronutrients, such as copper, sulfur, manganese, and zinc, and a 3% iron concentrate for deep greening. Additionally, the Humic DG – which is humic and fulvic acid – helps to enrich the soil and gives the plants and grass better access to nutrients.

This Professional PGF Fertilizer comes in the form of extremely fine granules, giving you 2X the number of particles per square foot of lawn. More particles result in a better and more uniform distribution. It also includes Anderson’s patented DG Technology, which allows nutrients to be absorbed more quickly by penetrating directly down into the root zone.

#2. Simple Lawn Solutions Ultimate 3-18-18 NPK Liquid Fertilizer 

Ultimate 3-18-18 NPK- Lawn Food Quality Liquid Fertilizer- Easy to Use Concentrated Spray- Any Grass Type- Summer & Fall Nutrients- Simple Lawn Solutions - Turf Hardiness & Root Vigor (32 Ounce)
  • High Phosphorus, High Potassium Lawn Food: If your lawn is showing symptoms of a Phosphorus and Potassium deficiency or if you want to maintain lawn health then this is the correct fertilizer for you!
  • Made With High Quality Feed Grade Ingredients: Nourish your lawn to its top potential with quality liquid lawn Nutrients.
  • Easy To Use: Designed to be easily applied. This high Phosphorus & Potassium Lawn Food gives your lawn the nutrients it needs for strong root development, vigor, and strength.
  • Can Be Used on All Grass Types: Including Bermuda, St. Augustine, Zoysia, Buffalo, Centipede, Palmetto & Bluegrass Lawns.
  • Easy to Use: Our 3-18-18 Lawn Fertilizer Food comes with a ready-to-use hose end sprayer that applies the perfect ratio of product for lawn applications. Covers up to 3,200 square feet, when using the attached sprayer.

The Simple Lawn Solutions Ultimate 3-18-18 NPK Liquid Fertilizer is next on our list of the top 6 fertilizers for use on St. Augustine Grass. This is a high phosphorus and high potassium lawn food, rather than the typical nitrogen-boosted fertilizers. If you think your lawn might be in danger of a phosphorus or potassium deficiency, or if you just want to maintain a healthy and strong lawn, this is a great fertilizer option. Phosphorus encourages the roots to grow thicker and deeper, meaning the grass will be more firmly rooted in the soil, and the potassium will help your lawn deal more effectively with any pests or weeds.

This fertilizer comes with a ready-to-connect sprayer nozzle, which can be connected to any hose and immediately start working. One can can cover up to 3,200 square feet of turf, and the concentration is already mixed to a perfect dilution ratio. It can be used on all grass types, including but limited to St. Augustine Grass.

#3. Simple Lawn Solutions Extreme Grass Growth Lawn Booster 

Extreme Grass Growth Lawn Booster- Liquid Spray Concentrated Starter Fertilizer with Humic Acid- Any Grass Type- Simple Lawn Solutions (32 oz. w/Sprayer)
  • Increase Vertical & Lateral Growth: Advanced Humic Acid Formula, Also Great for New Sod/Seeding
  • Nitrogen & Phosphorus Fertilizer: Commercial Lawn Growth Boosting Formula in a Ready-To-Use Hose End Sprayer
  • Use For Nutrient Deficiency, New Lawns and Lawn Repair: Concentrated Nutrients formulated to boost the growth of your lawn
  • All Grass types: Including Bermuda, St. Augustine, Zoysia, Buffalo, Centipede, Florida Palmetto, Bahia, Fescue, Ryegrass & Kentucky Bluegrass
  • Produced In The United States: Growth Booster is manufactured in the United States of America, by a family owned business with 25 years of former experience in the commercial professional turf industry.

The Simple Lawn Solutions Extreme Grass Growth Lawn Booster is another fertilizer that specializes in something else rather than nitrogen application. It has a 6-18-0 NPK ratio, so there is a fair amount of nitrogen present in it, and it will certainly get your lawn green and lush looking, but it primarily helps boost the growth of your lawn through the high 18% phosphorus concentrate. It also contains a boost of Humic Acid – this promotes the release of stuck nutrients and helps to increase fertilizer delivery and plant growth.

This fertilizer is best used for new or growing sod or seed plantings, or any lawn that is deficient in phosphorus or needs vertical or lateral growth. Again, this can comes with an attached sprayer that can hook up to a normal garden hose and can cover up to 3,200 square feet in one application.

#4. Doc’s Super Juice All in One Soluble Supplement Lawn Fertilizer

Super Juice All in One Soluble Supplement Lawn Fertilizer
  • New Improved Formula with 4% Iron !
  • Super Juice Lawn Fertilizer is the first ALL-IN-ONE, complete, balanced, lawn fertilizer that comes in a dry mix. Simply add to water and use a hose-end sprayer apply to your lawn.
  • Super Juice can be applied in a 14-2-4 ratio for a full acre of lawn, or most use it at half strength in a 7-1-2 ratio, and it treats two full acres. NO waste products or bio waste.
  • One bag of Super Juice will treat ONE ACRE* or 43,560 sq ft of lawn at the full concentration rate
  • Not sold in California

Doc’s Super Juice All-in-One Soluble Supplement Lawn Fertilizer is a fantastic all-round solution for any lawn or fertilizer needs, and it’s especially beneficial to St. Augustine Grass lawns. It has a 14-2-4 NPK ratio, which is considerably higher than the 3-1-2 ideal ratio, and also contains a variety of other minerals and micro nutrients, including sulfur, magnesium, copper, zinc, manganese, and a 4% iron concentration.

At its maximum concentration, one bag of the Super Juice will be able to fertilize one whole acre of land, which is around 40,000 square feet. For 80,000 square feet of treatment, dilute it halfway for a 7-1-2 ratio.  Simply add the dry mix to water and begin spraying, it’s that easy!

#5. Simple Lawn Solutions Advanced 16-4-8 Natural Liquid Fertilizer

Advanced 16-4-8 Lawn Fertilizer - Liquid Lawn Food Spring & Summer Concentrated Spray - Any Grass Type- Fish and Seaweed Kelp- Balanced NPK - Simple Lawn Solutions (1 Gallon)
  • Complete NPK Lawn Food: 16-4-8 is the perfect blend of key macronutrients. This lawn liquid food turf fertilizer also contains Seaweed & Fish
  • 16-4-8 Liquid Lawn Food is best to be used to maintain and feed your lawn, if you want to enhance the green of your lawn, if you are trying to boost vertical and lateral growth, and/or if your lawn is deficient in Macronutrients like Nitrogen, Phosphorus and Potassium
  • 1 Gallon Size covers 12,800 square feet. This complete Nitrogen, Phosphate, and Potash formula gives your grass nutrients for greening & growth while providing nutrients for roots, and strength. Use once a month alongside your regular fertilizer program
  • All Grass types: Including Bermuda, St. Augustine, Zoysia, Buffalo, Centipede, Florida Palmetto, Bahia, Fescue, Ryegrass & Kentucky Bluegrass
  • Produced In The United States: 16-4-8 is manufactured in the United States of America, by a family owned business with 25 years of former experience in the commercial professional turf industry.

The Simple Lawn Solutions Advanced 16-4-8 Liquid Fertilizer is another beneficial fertilizer for St. Augustine grass. The high amount of Nitrogen in the NPK ratio – four times as much phosphorus and twice as much potassium – guarantees that your St. Augustine lawn will grow lush and verdantly green. It also contains extra rich organic material in the form of seaweed and fish emulsion, allowing the soil to absorb nutrients more effectively. This organic fertilizer will increase the nutrient content of your soil, as well as all types of grass, including St. Augustine Grass.

It has a straightforward design that’s simple to connect to a hose and sprayed on your grass. It comes in a gallon form, as well as in 2.5 gallons. One gallon can cover up to 12,800 square feet with high quality fertilizer. This is an excellent fertilizer for keeping your existing grass healthy, as well as for enhancing the color of your lawn and increasing both vertical and lateral growth of the plant and grass life in your yard.

#6. Southern Ag Chelated Liquid Iron Fertilizer

Southern Ag Chelated Liquid Iron (128oz -1 Gallon)
  • Corrects Iron deficiency in flowers, vegetables, shrubs and trees
  • Use in lawns for a deep, rich green color
  • APPLICATION: Mix with water, apply as a drenching spray

The Southern Ag Chelated Liquid Iron Fertilizer is primarily a vehicle for preventing or correcting iron deficiencies in grasses and garden plants. It contains a 5% concentrate of iron, which is beneficial in turning your St. Augustine grass a deep and rich shade of green.

Simply mix about 1 tablespoon with a gallon of water – more if you need a higher concentration – and apply to your lawn as a foliar spray. For use on flowers, vegetables, trees, shrubbery, and all types of lawns.

In Conclusion

There are many different types of fertilizers on the market today, but we have narrowed it down to the six best options for St. Augustine grass in 2023. These fertilizers range from organic to synthetic, liquid to pellet form, and contain different NPK ratios. We hope we were able to give you a good enough description of each one, as well as a helpful buying guide, in order for you to make the best decision you can for your lawn and garden.

If you’re still a bit on the fence about exactly which fertilizer to get, we don’t think you can go wrong with the Professional PGF Complete 16-4-8 Fertilizer from The Andersons. It has everything your St. Augustine Grass will need to live up to its healthiest and fullest potential. Good luck with all of your lawn care, and happy gardening!

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Written by Linda Chan
Linda Chan is a passionate gardener and writer with a background in horticulture and landscape design. She has over 10 years of experience working in the lawn care industry and has a deep understanding of the science and art of keeping a lawn healthy and beautiful.