5 Best Fertilizers for St. Augustine Grass

40% of users selected Lawn Fertilizer Plus Iron, 20% selected Southern Triple Action, 20% selected Lawn Repair, 0% selected Roll Winter Survival and 20% selected Jonathan Green 11540. Every month we analyze your answers and change our rating.

St. Augustine Grass is a popular lawn grass in the southern United States, and it’s known for its resilience to drought conditions and low maintenance requirements.It requires regular fertilization to maintain a healthy root system and leaf growth, but not all fertilizers are created equal.

In this guide, garden experts will review the best fertilizers for St. Augustine Grass, including product reviews with useful tips about how often to apply different products so you can find what works best for your lawn!

Scotts Green Max Lawn Fertilizer Plus Iron Supplement – the Editor’s choice!

This fertilizer is suitable for all types of grass. It includes 5% iron, which promises to give your grass a deeper green color in three days. Scotts Green Max Lawn Food also contains nutrients like nitrogen and potassium. Those two synthetic components help the grass blade grow stronger and healthier from the inside out.

The dual-action, 2-in-1 formula feeds and supplements with iron, making it the perfect choice for busy homeowners who want beautiful lawns without having to spend hours caring for them.

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Scotts Turf Builder Southern Triple Action – the best for Southern lawns!

And if that’s not enough reason to try it out, the Scotts Apply Lawn can help you calculate the preparation for your specific needs. So don’t wait any longer – get ready to transform your Southern lawn with Scotts Turf Builder Southern Triple Action!

The triple formula, despite being a standard presentation that requires preparation, is worth trying. It’s very particular about the grasses it uses, making it easy to see whether it would work for your lawn. If your lawn is susceptible to weed growth, this is undoubtedly the solution for you.

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Scotts EZ Patch Lawn Repair For St. Augustine Lawns – the best for easy application!

Before application, the bare area must be dug up, dethatched, and watered. Apply, keep moistened, and wait for results to show after the dirt has been cleared from the spot and all of the dead grass and roots have been removed.

If you have a healthy but developing lawn but find patches of bare ground now and then, Scotts EZ Patch Lawn Repair For St. Augustine Lawns is an excellent fertilizer to use to repair the problem and nourish your grass. It’s designed specifically for St. Augustine grass lawns and comes with a ready-to-use mulch and fertilizer for lawn repairs.

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Jonathan Green & Sons 12414 Winter/Fall Fertilizer – the best for the winter season!

This fertilizer helps promote root growth, making your lawn more resilient in winter. In addition, it’s a great way to prepare your lawn for fall seeding.

Jonathan Green 12414 fertilizer is the perfect way to prepare your lawn for winter. The fertilizer will promote root growth, and it’s ideal for fall seeding. Moreover, it covers up to 15,000 sq. ft.! Make sure your lawn stays healthy all season long with this product.

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Jonathan Green 11540 Green Up Lawn Fertilizer – the best for sod lawns!

This fertilizer is high in phosphorus, which is important for the growth of new seedlings. Humates are also included in this product, which improves the performance, availability, and interchanging of plant nutrients with the soil.

Jonathan Green 11540 is the ideal choice if you want to fertilize your yard when seeding, over-seeding, or sod. It’s a critical moment in time, and this is one of the finest alternatives available for your yard throughout the growing process.

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The Buyer’s Guide

Main Features

Avoid fertilizers high in phosphorus since they might lead to zinc and iron shortages in your grass. Before you begin your St. Augustine lawn fertilizer schedule, do a soil test to find out what nutrients are required.

Slow-release vs. Quick Release Fertilizers

A slow-release fertilizer is insoluble, whereas a fast-release fertilizer is soluble. You’ll notice results after two weeks if you use a quick-release fertilizer on a St. Augustine lawn.

Slow-release fertilizers, on the other hand, take a longer time to produce results. With this type of fertilizer, you may wait up to 10 weeks for outcomes. There are several advantages over a fast-acting fertilizer in terms of duration.

Even at high temperatures, slow-release fertilizers rarely burn out the grass. Slow-release nitrogen fertilizers are less time-consuming to apply since you must reapply after 8-10 weeks.

The only disadvantage with slow-release nitrogen fertilizers for St. Augustine grass is that they are somewhat more costly. They, however, provide a rapid development effect on your lawn.

The reason why you should use a high-rated fertilizer for St. Augustine grass is that the fast development will help you combat weeds and several lawn ailments that result from poor nutrition [1].

Liquid vs. Granular vs. Water-Soluble

There are three basic types of lawn fertilizers: liquid, granular, and water-soluble. There is no “correct” option; the type of fertilizer that is best for your lawn is mostly a question of personal preference [2]:

1. Liquid. Many growers and groundskeepers choose to apply liquid lawn fertilizer as a fast boost of growth because it is quickly absorbed by the grass blades and begins working right away, encouraging new development. After applying liquid fertilizer to St. Augustine grass, results can be observed in as little as 3 or 4 days. The fertilizer can be obtained in a full-strength form or as a liquid concentrate for dilution and spraying via a pump-type garden sprayer. The disadvantage of liquid fertilizers is that they rapidly pass through and out of the grass, necessitating more applications than granular ones;
2. Granular. Granular fertilizers, which resemble little grains, are similar in composition to liquid fertilizers. They differ in that granular fertilizers are commonly released more slowly, allowing the grass roots to absorb nutrients over a longer period. Granules do not result in the same fast greening-up as liquid fertilizers but do require a less regular application. Granular fertilizers are applied with a spreader;
3. Water-Soluble. Even though this fertilizer is in the form of granules, it should not be spread on with a spreader. Water-soluble fertilizers are designed to be used with a hose-end dispenser that connects to a garden hose and dissolves and dilutes the granules before distributing them through a hand-held sprayer. Water-soluble fertilizer works similarly to liquid fertilizer in terms of how quickly it can green up the lawn;

Organic vs. Synthetic

Chemical and manufactured substances are used in most lawn fertilizers, but a few are entirely natural:

1) Organic/natural fertilizer

Synthetic fertilizers and organic natural fertilizers deliver the same nutrients, just from different sources. Earthworm castings and composted manure are two examples of natural organic fertilizers. Because it takes more effort to gather and process the components into fertilizer, they are generally more expensive than synthetic formulations. The benefits are that organic fertilizers are environmentally beneficial and aren’t likely to pollute waterways or harm aquatic life.

2) Synthetic/commercial/chemical fertilizer

Synthetic fertilizers are a collection of chemicals produced in a lab to replicate the nutrients found in nature. Synthetic fertilizers may be supplemented with important minerals present in healthy soil, such as calcium, magnesium, or boron. While lawns will benefit from both types of fertilizer, synthetic fertilizers that have a high nitrogen content can harm aquatic life if they run off into waterways.

N-P-K Ratio

Lawn and turf fertilizers are labeled with the amounts, by weight, of three major nutrients they contain: 

• nitrogen (N) promotes grass color and growth;
• phosphorus (P) promotes bud and seed development;
• potassium (K) encourages healthy plant growth;

Although all three are required for St. Augustine grass to thrive, nitrogen is the one that soils lack most.

The percentage of nitrogen in St. Augustine grass is usually greater than that of phosphorus and potassium. For example, a typical turf fertilizer has an NPK ratio of 15-1-5. 

When you look at lawn fertilizers, you’ll notice how many different NPK combinations they provide, but the majority are high in nitrogen [3].  

Application

It’s just as vital to know when to fertilize as it is to understand which fertilizer to use. Only in spring after the grass has turned fully green should you fertilize St. Augustine grass in the first place. 

Fertilizing it before that time might damage the grass. Apply an all-purpose lawn fertilizer with a high nitrogen content according to the product’s directions. Depending on the product, St. Augustine grass should be fertilized every 6-8 weeks after that.

St. Augustine grass doesn’t produce from seed, so it must be propagated via sod or plugs. 

Apply a lawn starter fertilizer with a balanced combination of nutrients, such as 10-10-10, to the dirt beneath the sod when beginning a new St. Augustine lawn. 

The fertilizer will be absorbed by the roots as they grow downward, improving plant health.

A month later, a high-nitrogen fertilizer can be applied, followed by applications as needed throughout the growing season. In the fall, stop fertilizing approximately 1 month before temperatures drop below 55F. St. Augustine grass goes dormant at this temperature and requires no fertilizer until spring [4].

How Big Is Your Lawn?

Make sure the fertilizer you choose will cover your yard adequately, and not just over a few applications. The majority of fertilizers must be reapplied every six weeks for optimum results, so don’t run out of supply mid-season. Most packages of fertilizer granules contain enough to treat at least 1,000 sq. ft. of lawn area, but this may not be enough for your needs. Determining the size of your lawn can help you narrow down the quantity of product you’ll need.

The area of a standard-size lawn is around 10,000 sq. ft., medium lawns about 5,000 square feet, and tiny lawns about 2,500 sq. ft. [5].

Soil Test for The Best Fertilizer Results

Fertilization is crucial in the development of St. Augustine grass and its maintenance since it helps to make it look its best and create a lovely lawn. St. Augustine grass is a warm-season grass with medium to high upkeep needs. It spreads via above-ground stolons, sometimes known as “runners”.

Warm-season grass is a popular choice in tropical and subtropical climates, producing a thick carpet-like sod. It pushes out other types such as Bermuda grass, argentine bahiagrass, and centipede grass.

The most common species of St. Augustine grass:

• Palmetto;
• Floratam;
• Captiva (resistant against southern chinch bag);
• Sapphire (has nice blue-green colored leaves);

The sod-propagating grass has a particularly high level of drought and shade tolerance. It thrives best in a tropical climate and frequently grows in marshes, lagoons, and beaches with flood water constantly available.

Have a soil test done before using any grass fertilizer or starting a seasonal lawn care fertilizer program for your St. Augustine grass (stenotaphrum secundatum).

The results of the soil test will “tell” you the soil pH and what the nutrient levels are for the 16 required elements for healthy growth and appearance. If any of these essential components are lacking or low in the soil, they can be “corrected” with fertilizers.

The three macronutrients that are the most important for St. Augustine grass are nitrogen (N), phosphorus (P), and potassium (K). The other macronutrients, magnesium, calcium, and sulfur, are required in lesser amounts.

Don’t believe that micronutrients aren’t vital; they are but in smaller amounts. Check with your local extension office for information on taking a soil sample and sending it to a lab for a comprehensive soil analysis. This will assist you in deciding which fertilizer is ideal for St Augustine grass in your yard [6].

When to Fertilize St. Augustine Grass?

Unless you live in South Florida, fertilizer should be applied twice a year, on average, from spring green-up to fall. In the spring before growth starts becoming active, watch out for applying fertilizer too soon. The same advice applies when fertilizing late in the season after the activity has decreased.

In the area where year-round temperatures are greater, St. Augustine grass grows all year and the fertilizer program is kept up all year. 

The first application of lawn fertilizer should be done around early April in the northern part of Florida (St. Augustine grass grows throughout the year). 

The first application of lawn fertilizer should be done in the northern region (Ocala north and across the southern US) around mid-April, approximately 3 weeks after the grass begins to turn green. The final fertilizer application of the season in the north should take place near the end of September. 

Final applications should cease earlier as you move further north. 

Tips for users: when applying fertilizer, never use more than 0.5 soluble nitrogen per 1,000 square feet per application. Too much can cause lawn fertilizer burn [7]. 

How much fertilizer does St. Augustine grass need?

Knowing the correct quantity of fertilizer is critical. You’ll end up with a sickly lawn if you apply too little, but not the lush, dark green St. Augustine grasses are known for. It’s also not an option to over fertilize your lawn.

You will have a much easier time applying fertilizer if you use a fertilization spreader to set the rate that is appropriate for the product you’re putting down.

The most essential guideline for fertilizing is this:

• Apply 1 pound of nitrogen for each 1,000 sq. ft. of St. Augustine grass lawn;
• This may not always be simple, since fertilizer bags have varying nutrient content percentages listed on their labels – frequently nitrogen, phosphorus, and potassium;
• To figure out how much nitrogen you’ll need for your lawn, divide the number on the fertilizer’s label by 100. This will tell you how much fertilizer you’ll need to apply to a 1000-square-foot area of your lawn within the recommended amount;

Too much nitrogen applied to your grass will harm it. Dry fertilizers, like salts, act as dehydrating agents and cause burned blades in plants. Brown leaf blades are a sure indication that you used too much nitrogen on your lawn [8].

FAQ

Is it possible to over-fertilize St. Augustine grass?

The St. Augustine lawn can absorb so much of its food source (nutrients from fertilizers) at once before it is unable to take in anymore. The truth is that the grass will, in fact, overfeed itself before it reaches a point where nutrient uptake may be stopped. 

And it’s due to this same overfeeding that excessive nutrients might become toxic in the St. Augustine grass and lead to sickness. 

When your grass is in such a delicate position, which may take months to recover from, depending on the season when the lawn damage occurred, it will be in a much more vulnerable state for longer. Diseases, weeds, and pest invasion are all far more likely [9].

How is fertilizer applied to a lawn?

Lawn fertilizer may be applied in a variety of ways. Fertilizing with a spreader provides uniformly distributed coverage than hand fertilization. 

Hand fertilization is prone to burns and pale regions that do not receive as much fertilizer as they should, owing to the concentration of the fertilizer and drop spreaders’ striping. 

Broadcast or rotary spreaders are simple to use and don’t leave stripes behind like drop spreaders.

Drop spreaders have the benefit of not putting fertilizer on the street, sidewalk, or driveway. You must make two trips over the lawn at right angles with a drop spreader. If you take your first pass in a north-south direction and then go west to east, for example. 

Water the lawn after applying fertilizer to ensure that all of the fertilizer is washed off. Watering cleanses the grass blades of any fertilizer, allowing them to burn less and ensuring that it sinks down into the soil where it may do its job. For how long as recommended on the label, keep children and pets off the grass [10].

Can fertilizer be applied to wet grass?

Water your lawn thoroughly a day or two before applying fertilizer. Fertilizer should be applied after the grass has dried. This is a very crucial second watering since it washes fertilizer off grass blades and into the soil. To allow rain to wash fertilizer into the soil, apply fertilizer during dry spells [11]. 

How do you make your St. Augustine grass thicker?

St. Augustine grass has above-ground stolons that spread and grow with its roots. If your lawn is thin and sparse, you may start a care program to make it thicker. But how can you encourage St. Augustine grass to spread quickly? 

To make St. Augustine grass spread fast and thicken up, sow sod in late summer in well-draining soil with a pH range of 5.0 – 8.5 with sods planted in early summer in well-draining soil with a pH range of 5.0 – 8.5.

When putting down St. Augustine grass sod, make careful not to push the lawn too much and too soon with excessive fertilizer or weed control herbicides until the grass is at least 50% greened up [12]. 

Why is my St. Augustine grass turning yellow?

Because St. Augustine grass requires many necessary minerals from the soil, if your yard is unable to provide these nutrients, it will begin to fade.

Make sure to apply the finest fertilizer for St. Augustine grass on a regular basis to regain your lawn’s natural green glow. Slow-release fertilizers are an excellent choice since they guarantee feeding and nutrient seepage for your lawn between applications.

A lawn-feeding product for St. Augustine grass that incorporates a mix of iron and nitrogen is required to keep everything green and lush. 

Spraying your lawn with plant sulfates at a concentration of 2 ounces to 3-5 gallons of water per 1,000 sq. ft. may also help you maintain a greener yard by encouraging growth [13].

How much sunshine does St. Augustine grass need? 

If you want to get access to naturally occurring ingredients, keep your St. Augustine grass in full sun. If there are a lot of shady areas developing due to trees or bushes, this might be the source of your yellowing St. Augustine grass problem.

A sunny St. Augustine grass yard is a beautiful thing – choose fences that don’t block the sun, and trim back the verge to allow your grass to enjoy full light. When St. Augustine grass has access to at least 6-8 hours of direct sunlight, it flourishes [14].  

Is Epsom Salt good for St. Augustine grass?

Epsom salts are not only beneficial for a bath, but also for your St. Augustine grass. Applying Epsom salt to your yard will not only improve the soil’s nutrient levels, but it will also function as a natural fertilizer and pesticide that won’t harm other plants.

Because Epsom salt effectively binds iron, nitrogen, and other required sulfates, it is the ideal alternative for a natural applicant due to its high iron and mineral content.

Furthermore, Epsom salt is high in magnesium, which will assist to balance the soil’s pH level and encourage stronger root systems and greater grass development for your St. Augustine grass.

To apply the Epsom salt, simply fill your lawn spreader with about a half-pound of Epsom salt for every 100 square feet of grass and distribute it to the yard. Don’t be concerned if the Epsom salt is sparser into your garden trenches; it should function as a natural pesticide there and repel a range of common pests.

It’s most successful when used in the spring or fall to avoid weed development during the height of summer [15]. 

What month should I fertilize St. Augustine grass?

The precise month when it is appropriate to fertilize your St. Augustine grass depends on local and regional weather phenomena, as well as your location. However, there are some simple rules for determining when your St. Augustine grass is ready to be fertilized.

The first fertilization should take place approximately two to three weeks after the final frost, once the grass has resumed growing green. This is when St. Augustine grass breaks its winter dormancy period and needs extra support in order to be ready for summer.

Because this will be the first fertilization of the season, you want to make sure there is plenty of food for the soil to re-grow after the winter months. Fertilize all your St. Augustine turfgrass with a high-nitrogen solution and water it thoroughly but not excessively.

Stick to a regular irrigation schedule rather than resort to only one or two watering sprees. Let your soil become saturated and then fully absorb the water afterward, rather than relying on just one or two sprinkles.

Rather than leaving nutrients to accumulate in ineffective clumps, a regular watering schedule will help your soil fully utilize the fertilizer components.

What is the best topsoil for St. Augustine grass?

It’s best to use clean, free-flowing sand or sandy loam soil for the top dressing for a St. Augustine grass lawn. This will help keep the soil wetter. Use as much organic material as possible to ensure that you don’t get too much water sitting in your soil [16]. 

Why is my St. Augustine grass turning lime green?

The most common reason for death is a lack of nutrients in the soil. Nitrogen and iron are crucial to keeping balanced into your lawn diet, particularly in sandy soil [17]. 

Can you put too much nitrogen on St. Augustine grass?

Excess nitrogen, caused by fertilizer over-application, can cause rapid, lush growth and a shrunken root system. In severe situations, too much quick-release nitrogen might harm the leaf tissue and kill the plant. A lawn with a nitrogen deficiency will eventually become yellow in color because of this [18]. 

Is lime good for St. Augustine grass?

Fertilize and add lime or sulfur-based on a soil test. The optimal pH for growing St. Augustine grass is 6 to 6.5, according to the University of Kentucky College of Agriculture’s Extension Service. If the soil’s pH is higher than 6.0, sulfur can be used to decrease it. Every 1000 sq. ft. of turf should receive 5 pounds of powdered sulfur pellets.

In three months, recheck the soil’s pH and see what difference it has made. It might take several years to make a substantial change in soil pH. Soils in the hill country are typically acidic, but they do require lime applications on occasion.

2 to 4 pounds of actual nitrogen per year, on 1000 square feet of turf, is required for St. Augustine grass lawns. For those growing St. Augustine grass on sandy soils, a higher rate may be used; for those gardening on clay soil, the lower rate can be utilized. In between fertilizer applications, a soluble iron product like iron sulfate or a commercial chelated iron will improve the green hue without stimulating growth.

St. Augustine grass should be fertilized three times during the summer, as advised below. St. Augustine grass is, however, generally fertilized only twice throughout the growing season (early May and early July) on clay soils in the piedmont and midlands of South Carolina [19]. 

Is peat moss good for St. Augustine grass?

The ideal method for stimulating the growth of your grass is to use a 1-inch layer of Canadian sphagnum peat moss. This was investigated years ago by Dr. Phil Colbaugh, a plant research scientist who is now retired. Dr. Colbaugh recommends applying the peat in late April or May, and he has shown that treated lawns benefited significantly from it [20]. 

Is sand good for St. Augustine grass?

Some turfgrass species thrive in sandy soil particularly well. Centipede grass, carpetgrass, and St. Augustine grass are among them. Top dress an uneven St. Augustine lawn with sandy loam or clean flowing sand to establish it. The sand is then leveled and watered into the St Augustine lawn to make deeper indentations that are more than 2 to 3 inches deep safe [21]. 

What temperature kills St Augustine grass?

While St. Augustine provides substantial, tough coverage throughout the spring, summer and early fall, it withers in the low 30s. It will die if the temperature goes below 25F [22]. 

Why are my lawn stripes after fertilizing?

The stripes are caused by misaligning the spreader with each pass. An “edge” where the fertilizer strikes the lawn is common on drop and broadcast spreaders. The stripes themselves result from overlapped or gaps in the fertilizer, creating green light and dark bands [23].

Useful Video: Best Fertilizer for St Augustine Grass – Houston Grass – Missouri City Pearland

Final thoughts 

You may be wondering how often to fertilize your St. Augustine Grass, and that depends on the fertilizer you choose. If you want a product with high nitrogen content for rapid greening of new growth in springtime, plan to apply it once every four weeks in March through November (six applications total). However if you prefer something with fewer chemicals like organic slow release or composted products, then one application per year should do the trick! 

For more information about what kind of fertilizer is best for your St. Augustine lawn’s needs please read our guide where we review all kinds of different options – from synthetic chemical based products to natural plant-based products that are good for both people and planet alike.

References:

1. https://www.crabgrasslawn.com/best-fertilizer-for-st-augustine-grass/
2. https://www.bobvila.com/articles/best-fertilizer-for-st-augustine-grass/
3. https://www.bobvila.com/articles/best-fertilizer-for-st-augustine-grass/
4. https://www.bobvila.com/articles/best-fertilizer-for-st-augustine-grass/
5. https://gardenandgrass.com/best-fertilizer-for-st-augustine-grass/
6. https://plantcaretoday.com/fertilizer-st-augustine-grass.html
7. https://plantcaretoday.com/fertilizer-st-augustine-grass.html
8. https://www.crabgrasslawn.com/best-fertilizer-for-st-augustine-grass/
9. https://saintaugustinelawncare.com/st-augustine-lawn-care/268-over-fertilizing-st-augustine-grass.html
10. https://www.gardeningknowhow.com/lawn-care/lgen/lawn-fertilizer-tips.htm
11. https://www.hgtv.com/outdoors/landscaping-and-hardscaping/lawns/14-tips-for-fertilizing-your-lawn
12. https://lawnmodel.com/make-st-augustine-grass-spread-grow-thick/
13. https://gardenandgrass.com/best-fertilizer-for-st-augustine-grass/
14. https://gardenandgrass.com/best-fertilizer-for-st-augustine-grass/
15. https://gardenandgrass.com/best-fertilizer-for-st-augustine-grass/
16. https://bovees.com/how-to-make-st-augustine-grass-spread-quickly/
17. https://grasslawnscare.com/make-st-augustine-grass-greener
18. https://www.thespruce.com/closer-look-at-nitrogen-2152981
19. https://hgic.clemson.edu/factsheet/st-augustinegrass-maintenance-calendar/
20. https://neilsperry.com/2010/05/st-augustine-problems/
21. https://findanyanswer.com/does-st-augustine-grass-like-sand
22. https://southaustinirrigation.com/caring-st-augustine-grass-lawns-cooler-weather
23. https://lawnpride.com/how-to-avoid-common-fertilizer-mistakes/

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