Best Fertilizer For St Augustine Grass | How And When To Use

St. Augustine grass (Stenotaphrum secundatum) is a rough-textured turf, typically found coloring landscapes, in temperate climates, a gray-green hue.

Named after Saint Augustine, Bishop of Hippo, it was first discovered, in the 1700s, growing along the Floridian shores of the Atlantic Ocean. Near a town that bears the same name. Today, this durable sod can be found along tropical shores in Africa, Australia, and southeast Asia, where it’s known as Buffalo grass.

All three St Augustine varieties (as well as 11 different cultivars) are known for their resiliency. More frequent bouts of excessive rain and heat waves are moving growers to be equally resilient in ensuring that their grass holds up. Which they do, with the help of the best fertilizer for St. Augustine grass.

Best Fertilizer For St Augustine Grass

Best Liquid Fertilizer

Simple Lawn Solutions Liquid Fertilizer 15-0-15

Pre-mixed liquid formula, complete with a spray hose attachment that offers coverage of up to 3,200 sq. ft on established St Augustine lawns. Suitable for use in phosphate restricted areas and on other southern lawns such as Zoysia, Bermuda, and Centipede.

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Best Granular Fertilizer

The Andersons Fertilizer with Humic 16-4-8

Great coverage on well-established lawns where soil nutrients are lacking. This granular feed offers a slow release of macro and micronutrients for up to 8 weeks.

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Best Weed & Feed

Scotts Turf Builder Bonus S 29-0-10

Perfect for established St Augustine that is looking a little lackluster and is prone to crabgrass and other perennial weed outbreaks during the growing season. Provides strong root growth and vibrant color in just 1-2 weeks. 

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Choosing The Best Fertilizer For St. Augustine Grass

Coveted for its ability to thrive in different environments, this broad-leafed grass is very forgiving. But, it still needs proper nutrients to remain healthy.

Once established, St. Augustine grass needs nitrogen to form all those bright, green blades. But, when new, higher phosphorus is needed for a sturdy and robust root structure.

In addition to proper nutrition, keeping unruly weeds at bay ensures that your lawn has optimal access to it.

The key to a solid fertilizer choice lies in understanding the difference between “weed and feed” products and straight fertilizers.

Fertilizer vs Weed And Feed

In my experience, weed-and-feed products are fine if you’re shooting for getting things done in less time. But, for a healthy, durable lawn, you’ll want to de-weed and feed separately. Here’s why…

Weed-and-feeds are a combination of herbicide (plant killer) and fertilizer (plant nourisher). These two processes can’t realistically happen at the same time. The herbicide will often over-power the fertilizer and hurt your grass.

Organic Vs Synthetic                 

Choosing between organic and synthetic fertilizers is simply a matter of preference. However, a basic understanding of how each works and affects your environment will support an informed decision.

Organics are plant/animal-based and offer nutrients while improving the soil. Many also come without the risk of over-fertilizing or environmental contamination.

Inorganics are manufactured with synthetic chemicals and often result in faster growth. But, come with over-use risks.

Liquid Vs Granules

The best fertilizer for St. Augustine grass can come in liquid or granular form. Granules are slow releasing, can last for several months, without needing to be watered in, and are less likely to leach into nearby water sources.

Liquids are fast-acting and give you more control over how much your lawn is fertilized and when. Applied with a simple hose attachment, nutrients are carried directly to the roots.

How do I make my St. Augustine grass green?

Lawns that receive adequate sunlight, water, and nutrients will naturally respond with healthy colors.

But, there are a few things you can do to increase color vibrancy even further:

1. Maintaining consistent levels of nitrogen in the soil will enhance blade color.
2. Applying chelated iron can also amplify color, but without the risk of excess growth.

High Nitrogen Lawn Fertilizer

I tend to lean toward the chelated iron option because I feel it’s the safest option to green up your lawn. Applying too much nitrogen can have dire consequences.

Nitrogen is known for promoting rapid growth and enhancing color. But often, high nitrogen fertilizers can lead to forced growth that leaves your lawn vulnerable to pests, disease, and environmental stresses. 

Using 10-10-10 Fertilizer For St. Augustine

Soil testing is really the only way to determine how to properly fertilize your St. Augustine grass. The results will show you what nutrients are already in your soil and what needs to be added.

If it shows you have fertile soil, a 10-10-10 fertilizer will provide a steady stream of all that your lawn requires to stay healthy.

7 Best St. Augustine Grass Fertilizer Reviews

To determine the best fertilizer for St. Augustine grass, I’ve done some testing that includes product details and the pros and cons of each to allow you an informed decision. I‘d like to share the 7 options that came out on top, based on performance and ease of use. 

1. Simple Lawn Solutions Liquid Fertilizer 15-0-15

Best Liquid Fertilizer

• Type: Pre-Mixed Liquid
• Application: Hose End Spray
• Coverage: 3200 Sq.Ft.
• N-P-K: 15-0-15

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PROS

• Great option for use in phosphate-restricted zones
• Equal support for strong roots and vibrant color

CONS

• Sprayer may clog if not cleaned after use

This is my top pick liquid lawn feed and is an especially good option for those with well-established St Augustine or for lawns planted in a phosphate-restricted zone.

With equal parts of nitrogen and potassium, you can expect enhanced new blade formation and vibrant color above the ground and a strengthening of the expanse of roots below.

It also has the addition of humic acid, a vital micronutrient that supports the uptake of macronutrients and enhances color as well as overall health.

This lawn feed couldn’t be simpler to use. It comes with a hose-end spray attachment (that will need flushing out after each use) and is ready to use straight from the container.

2. The Andersons Fertilizer With Humic 16-4-8

Best Granular Fertilizer

• Type: Granules
• Application: Push Spreader
• Coverage: 5000 Sq.Ft.
• N-P-K: 16-4-8

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PROS

• Ultra-fine pellets for more effective coverage
• Slow-releasing for a consistently greener lawn

CONS

• Not recommended for nitrogen-rich soil

If a soil test reveals poor soil beneath your St. Augustine turf, this professional-grade option can give it just enough phosphorus to revitalize a tired root system and jumpstart new growth.

Fortified with iron plus other vital micronutrients including humic and fulvic acids, these slow-release granules showed impressive results in lawns with sloped areas where soil nutrients are often lacking.

With adequate watering or rainfall, a greener, thicker St. Augustine lawn can begin to appear in a matter of 6-14 days.

This is my top pick granular feed for lawns. It is great value for money, offering coverage of up to 10,000 sq ft and a slow release of nutrients for up to 8 weeks.

3. Scotts Turf Builder Bonus S 29-0-10

Best Weed & Feed Granules

• Type: Granules
• Application: Push Spreader
• Coverage: 5000 Sq.Ft
• N-P-K: 29-0-10

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PROS

• Builds strong roots to strengthen against heat and drought
• Kills crabgrass and other listed lawn weeds

CONS

• Not for use on Bermudagrass

To be fair, I included some weed-and-feed options to see how they performed. Per the label, there is more fertilizer in this than weed killer and is specially formulated for warm-season grasses.

Surprisingly, this nitrogen/potassium combo resulted in visible, new growth, on my own St. Augustine grass, after just one week. After 2 weeks, scattered spots of crabgrass began browning.

Results are better when this product is used on established grass. I would avoid using it on fresh sod or new seedlings due to the high nitrogen content. Remember, new grass needs help from the nutrient phosphorous to help establish strong and healthy root systems.

4. Scotts Turf Builder Lawn Food 32-0-4

• Type: Granules
• Application: Push Spreader
• Coverage: 400m x 800m Sq.Ft.
• N-P-K: 32-0-4

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PROS

• Builds strong, deep roots, and improves water and nutrient absorption
• Won’t burn lawns when used as directed

CONS

• Overuse may result in lawn browning

Unlike my previous Scotts pick, this one is straight fertilizer. But, I saw the same great results (minus the browning crabgrass) starting at around the 5-day mark. And I didn’t have to apply it again for 2 months.

If your area enforces a watering ban in times of drought, even though turfs like St. Augustine can take a beating. These granules can help increase drought tolerance and when watering is allowed again, another dose can help green it right up.

5. The Andersons PGF Balanced Fertilizer 10-10-10

• Type: Powder
• Application: Hose End Spray, Spreader
• Coverage: 5000 Sq.Ft.
• N-P-K: 10-10-10

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PROS

• Can be used any time during the growing season
• Quick-releasing for immediate nutrition

CONS

• May not be as effective on poor soil

This well-balanced option carries the same professional grade as others from The Andersons and is the best fertilizer for summer grass grown in fertile soil.

It’s water-soluble, so I just mixed the small particles with water, as recommended, and applied it with my hose attachment.

The quick release of nitrogen provided immediate nutrition to the roots of my lawn, without overwhelming it. The addition of iron and other vital micronutrients improved color equally as fast.

6. Simple Lawn Solutions Lawn Booster 6-18-0

• Type: Pre-Mixed Liquid
• Application: Hose End Spray
• Coverage: 3200 Sq.Ft.
• N-P-K: 6-18-0

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PROS

• Formulated for newly seeded or sodded lawns
• Quick-releasing for faster root establishment

CONS

• Not recommended for established lawns

My first pick from Simple Lawn Solutions was for established lawns, this is my pick for the best fertilizer for St. Augustine grass that’s newly seeded or sodded.

The higher phosphorus in this pre-mixed liquid solution encourages the growth of robust and durable roots. While supporting new blades that grow from them with just 6% nitrogen.

7. Scotts Liquid Turf Builder Fertilizer 29-0-2

• Type: Pre-Mixed Liquid
• Application: Hose End Spray
• Coverage: 2000 Sq.Ft.
• N-P-K: 29-0-3

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PROS

• Made for use on any type of grass
• Increases drought and traffic tolerance

CONS

• Sprayer may clog if not cleaned after use

Another easy-to-use pick is this liquid option from Scotts. It’s flexible enough to be used on warm or cool-season grasses and allows you to feed, green up and water your lawn at the same time, in spring, summer, or autumn.

After a few applications, the St. Augustine grass I tested this on held up quite nicely to high seasonal temperatures, drought, and the wear-and-tear of summer activities.

The small size of the bottle can be deceiving. During testing, it adequately covered an entire 2000 sq ft area.

How To Fertilize St. Augustine Grass

How to fertilize your St. Augustine lawn depends on its age and condition. Do you have a newly planted seed, new sod, or an established lawn?

New grass seeds need more phosphorus to encourage strong, healthy root systems. Once established, a nitrogen-rich lawn feed will give you that lush, green, stress-tolerant look.

Just make sure you hold off using a weed-and-feed product on St. Augustine seedlings. It’s not something I’d recommend as these can severely damage tender grasses while encouraging vigorous growth in any existing weeds.

How often should I fertilize my St. Augustine grass?

The frequency will differ depending on the application method. When using a liquid option, St. Augustine grass should be fertilized roughly every 6-8 weeks.

Granules only need to be spread once or twice per season. How much to apply will depend on a quality soil test. Use this to find out what nutrients are already present in the soil and what is lacking.

How do I apply fertilizer to St. Augustine Grass

Liquids should be applied just after the first spring mowing. Immediate root absorption will encourage lush, new growth. Just spray in even rows as you walk across your lawn.

Granules are applied via a drop or broadcast spreader. Each product should reflect a recommended spreader setting on the label.

When To Fertilize St. Augustine Grass

Successful fertilization starts with a low nitrogen/high phosphorus fertilizer, in spring, after the last predicted frost.

In summer, a switch to high nitrogen will refocus energy toward thick, sturdy blade production. The addition of iron will promote a more vibrant green color without stimulating excess growth.

Nitrogen applications in autumn could trigger new growth that may be fatally damaged by an early frost.  But, potassium is recommended to encourage winter hardiness.

St. Augustine Grass Fertilizer Schedule

Devising a consistent fertilizing schedule can be challenging. But, flexible strategies can include familiar practices. Here are some recommendations for each season:

Spring

Successful lawn fertilization should start with a soil test. This will reveal what nutrients are already beneath your lawn and what needs amending.

If you have fertile soil, a 10-10-10 NPK may be all you need. If not, remember that lawns require more phosphorus in spring and fertilize accordingly.

Summer

How much fertilizer to apply now again depends on soil type and existing nutrient availability. But, applying phosphorus should by now be at a minimum.

A 29-0-3 NPK, or similar, will encourage lush grass blades. Higher amounts of nitrogen are especially effective on lawns grown in sandy or clay soils.

Fall

Fall is when nitrogen and phosphorus are put away and potassium is increased, to encourage winter hardiness. This can be applied at the same rate as of summer nitrogen, 1 – 1.5lbs per 1000 sq ft. Apply this at least every 4-6 weeks prior to the first expected frost. 

How do you revive St. Augustine grass?

There’s no ‘quick fix’ for reviving St. Augustine grass. But, it’s a fairly simple 3-step process that’s well worth the effort.

• Give your lawn a minimum of 1-1.5” of water per week, for at least 6 weeks.
• Following a soil test, apply a lawn fertilizer that fills any deficiencies.
• Once re-established, follow up with an effective pesticide, if pests were found to be the problem.

Understanding Fertilizer Ratio N-P-K

Every fertilizer label reflects a three-numbered formula. This is the N-P-K of that product, indicating its proportions of nitrogen, phosphorus, and potassium. For example, a 16-4-8 NPK has 16% nitrogen, 4% phosphorus, and 8% potassium. Every plant requires these three elements in order to thrive. Just in different proportions or NPK ratios.

Each of these macronutrients plays a vital role in cell formation, photosynthesis, and nutrient distribution. All working in tandem to create a healthy, lush lawn.

Nitrogen

Nitrogen plays a vital role in the growth of healthy grass, by fueling the production of chlorophyll. This gives grass its green color and ensures that photosynthesized energy is available to convert starches and carbohydrates into food.

This multi-tasking macronutrient also fuels the proteins and enzymes that regulate water and nutrient uptake. High nitrogen fertilizer is typically formulated for lawns and other plants where foliage is the primary focus.

Phosphorus

Phosphorus is key in the critical process of photosynthesis. Once the chlorophyll is produced, this macronutrient triggers the energy captured by chlorophyll to convert starches and carbohydrates into food.

Another important (and more visible) function of phosphorus is the creation of abundant blooms in flowering grass varieties, as well as robust root systems.

Phosphorus begins its work at the cellular level. Constructing those same proteins and enzymes that nitrogen uses to regulate water and nutrients.

Potassium

Potassium is responsible for the vital circulation of water, nutrients, and photosynthesized food throughout your lawn. It also activates the proteins and enzymes that were formed using phosphorus and nitrogen to build a healthy turf structure.

Proper amounts of potassium contribute to a plant’s resistance to disease and extreme heat and drought by helping them to conserve moisture. And is especially effective in encouraging tolerance for even the coldest winters while lawns lie dormant.

Verdict: Best Fertilizer For St. Augustine Grass

The verdict is in! The best fertilizer for your St. Augustine lawn will be the one on my list of picks that caters to your lawn’s age, the condition of your soil, and your preferred application method.

Will it be the Simple Lawn liquid solution option for established grass that works immediately to form strong roots? Or the professional-grade granules from The Andersons that revive tired roots with just a walk around your lawn? Alternatively, is it a weed and feed solution you need for your tired-looking, weed-infested St Augustine? If so, you need Scotts Turf Builder.

Best Liquid Fertilizer

Simple Lawn Solutions Fertilizer 15-0-15

Pre-mixed liquid formula, complete with a spray hose attachment that offers coverage of up to 3,200 sq. ft on established St Augustine lawns. Suitable for use in phosphate restricted areas and on other southern lawns such as Zoysia, Bermuda, and Centipede.

Check Price

Best Granular Fertilizer

The Andersons Fertilizer with Humic 16-4-8

Great coverage on well-established lawns where soil nutrients are lacking. This granular feed offers a slow release of macro and micronutrients for up to 8 weeks.

Check Price

Best Weed & Feed

Scotts Turf Builder Bonus S 29-0-10

Perfect for established St Augustine that is looking a little lackluster and is prone to crabgrass and other perennial weed outbreaks during the growing season. Provides strong root growth and vibrant color in just 1-2 weeks. 

Check Price

Whichever one suits you best, may you enjoy a lush, green lawn for the seasons to come?

FAQ’s St. Augustine Grass Fertilizer