Best Fertilizer for St. Augustine Lawns in 2022: 5 Trustworthy Products, Reviewed

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Saint Augustine grass is common pretty much across the United States as well as in South America and even certain parts of Africa. It’s much prized by those who like to take pride in their lawns for showing excellent tolerance to lack of sun as well as heat and high soil salt content. It comes in a number of varieties, each with its preferred habitats as well as strength and witnesses.

Product
Top Pick
Ultimate 3-18-18 NPK- Lawn Food Quality...
Runner-Up
Urban Farm Fertilizers Liquid Lawn...
Premium Choice
SeedRanch St. Augustine Lawn 24-2-11...
Prime
-
-
Pros
You don’t need any specialized equipment to use it
The conservative high-nitrogen formula is good all year round
The granules last for more than a month
Top Pick
Product
Ultimate 3-18-18 NPK- Lawn Food Quality...
Prime
Pros
You don’t need any specialized equipment to use it
My preview
Runner-Up
Product
Urban Farm Fertilizers Liquid Lawn...
Prime
-
Pros
The conservative high-nitrogen formula is good all year round
My preview
Premium Choice
Product
SeedRanch St. Augustine Lawn 24-2-11...
Prime
-
Pros
The granules last for more than a month
My preview

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Still, all of them need proper fertilization in order to thrive. Read below to find out what the best fertilizer for St. Augustine grass is and how to choose one.

5 Best Saint Augustine Grass Fertilizer Options Reviewed

  1. Simple Lawn Solutions 3-18-18 Lawn Food – Top Pick
  2. Urban Farm Fertilizers 13-1-2 Liquid Lawn Fertilizer – Runner-Up
  3. SeedRanch St. Augustine Lawn 24-2-11 Fertilizer – Premium Choice
  4. GS Plant Foods Organic Liquid Humic Acid
  5. Southern Ag Chelated Liquid Iron

What is the best fertilizer for St Augustine grass specifically? Here are my reviews of five great products in this category to help you navigate the fertilizer market while keeping the needs of your turf variety in mind.

1. Simple Lawn Solutions 3-18-18 Lawn Food: Top Pick Liquid Fertilizer for St Augustine Grass

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Some of you might be surprised by this fact, but fertilizing isn’t all about nitrogen! It’s not uncommon for lawns to suffer from phosphorus and/or potassium deficiency, manifesting in weak roots and discolored grass blades, sometimes with diebacks.

If you feel like this is the case with your lawn, the 3-18-18 formula of this Lawn Food can prove extremely beneficial for your St. Augustine grass. This is my absolute favorite for visibly withering lawn vegetation of pretty much any kind. It helps the turf recover quickly, growing lush and green where it used to be sparse and burned-out. The potassium in it also increases hardiness.

The liquid formulation of this fertilizer means you need to re-apply it once in a couple of weeks. This is not a difficult task due to the convenient bottle design.


ADVANTAGES:
  • The low-nitrogen formula targets common deficiencies; you get strong roots and beautiful grass blades.
  • This fertilizer quickly improves the appearance of your lawn.
  • The liquid formulation makes the application easy to control.
  • You don’t need any specialized equipment to use it.
DRAWBACKS:
  • The formula needs more frequent reapplication than many granular options.
  • There are cheaper products in the liquid fertilizer category.

2. Urban Farm Fertilizers 13-1-2 Liquid Lawn Fertilizer: Runner-Up Solution for Fertilizing St Augustine Grass

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Another all-purpose fertilizer on the list, this Urban Farm Fertilizers product uses a more common formula that’s high in nitrogen, namely 13-1-2. It’s still far from being very concentrated, but its key purpose is promoting foliage growth. To further enhance the benefit for your St. Augustine grass lawn, it comes with iron included in the formula.

What the iron does is give the turf a beautiful deep green color. I have a friend who wouldn’t use any kind of “chemical” fertilizer on his lawn until it all turned a lifeless pale hue of green, and then it was this product that brought it back to life. He chose it partly because it covers 5,000 square feet of turf at least 8 times.

Application is a breeze using a hose-end spray. You could also use a tow-behind tank for convenience.
I find the results produced by this fertilizer on St. Augustine grass somewhat less impressive by the outcome of regularly using my top pick. The cost is much lower, too, though, given the coverage.


ADVANTAGES:
  • Added iron improves turf color.
  • The conservative high-nitrogen formula is good all year round.
  • Mixing the solution is not difficult.
  • One bottle covers a lot of turf.
DRAWBACKS:
  • You need to apply it often and generously to see results.

3. SeedRanch St. Augustine Lawn 24-2-11 Fertilizer: Premium Choice Saint Augustine Grass Fertilizer

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In case you are willing to give your St. Augustine grass some special treatment, SeedRanch has a dedicated solution for this kind of turf. It comes with a generous share of nitrogen as well as added potassium. The latter fights potential burned-like yellowings that are characteristic of potassium deficiency.

Unlike the previous liquids, this is a granular formula that tends to release the nutrients at a slower pace. I did have to wait for several weeks when I tested it on my St. Augustine grass, but the results were very real when they arrived. With 6% of added iron, the fertilizer makes the turf emerald green, lush, and thick.

The 50 lbs extra large pack will cover around 12,000 square feet, making it just reasonably pricey if you consider the effect as well as the fact that it works for a couple of months and not weeks when it’s on your turf.


ADVANTAGES:
  • The high-nitrogen formula provides long-lasting balanced nutrition.
  • The grass becomes dark green due to the iron.
  • The granules last for more than a month.
  • One pack will cover around 12,000 square feet.
DRAWBACKS:
  • The formula is likely to take some time to act.

4. GS Plant Foods Organic Liquid Humic Acid: A Simple Answer to How Often to Fertilize St Augustine Grass

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If you aren’t sure if you’ve been fertilizing your lawn too rarely but don’t want to overdo it, you can use this humic acid to enhance the effect of the other fertilizers.

The key purpose of this formula is to increase nitrogen uptake as well as that of other essential nutrients. It also promotes healthy root development and plant immunity, making your St Augustine grass less susceptible to diseases.

One ounce of the liquid is mixed with around a gallon of water and can be applied easily using a hose sprayer. This is an organic solution that improves overall soil quality and turf root state when used in combination with pretty much any fertilizer.

I have been using it along with the top pick for quite a while, and I’ve never experienced an immunity-related problem with my lawn.


ADVANTAGES:
  • Humic acid improves nutrient uptake from existing fertilizers.
  • The formula makes grass roots healthier and improves turf immunity.
  • The liquid is easy to mix and apply.
DRAWBACKS:
  • The formula works best in combination with other fertilizers, which is pricey.

5. Southern Ag Chelated Liquid Iron: A Powerful Supplement to Use with a St. Augustine Grass Fertilizer

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If your fertilizer of choice doesn’t contain iron along with the vital nutrients, you might want to feed it some using this Southern Ag product. This is nothing but 5% iron in a liquid form.

I tried it along with a number of iron-free solutions to keep the turf emerald green rather than yellow, and it has never failed me. However, this will only work provided that the soil pH is suitable for your grass variety; otherwise, the yellowing might have little to do with iron deficiency.

The product is a fast-acting liquid that needs to be mixed with water. You need a pint per 1,000 square feet of turf mixed with enough water to drench the soil thoroughly.


ADVANTAGES:
  • The solution works quickly.
  • If the grass is yellow due to iron deficiency, it restores its deep green color quickly.
  • The product can be combined with other fertilizers.
DRAWBACKS:
  • This is a specialized product that only targets iron deficiency.

St. Augustine Grass Fertilizer Buyer’s Guide

St. Augustine Lawn

It’s not easy to tell what kind of fertilizer for St Augustine grass will work best on your lawn without knowing the exact setting. However, there’s a whole set of rules of thumb to help you grow some picture-perfect vegetation without too much effort.

Selecting lawn fertilizers for St Augustine grass

Generally, fertilizers using a nutrient ratio of 3-2-1 (nitrogen to phosphorus to potassium) are recommended for St. Augustine grass. This doesn’t preclude other formulas which might be skewed towards a certain nutrient based on the results of a soil test, though.

As a supplement, many lawn owners like to feed their St. Augustine a bit of iron to give it a deep green hue. Some fertilizing products come with this included in the formula to spare your time.

Lawn after Urban Farm Fertilizers

Both liquid and granular formulations can work well, the former being easier to apply in a uniform way and control but providing less long-lasting effect while the latter take time to apply and usually ensure a slow release of nutrients over time.

When it comes to choosing between organic and synthetic fertilizers, remember that natural formulas are generally slower but better in the long run. However, feel free to use an approved synthetic solution as long as it’s suitable for the grass variety of your choice.

When to fertilize St Augustine grass

The most vital consideration is not to start fertilizing your lawn too early. Soil temperature at a depth of 4 inches must be consistently not lower than 65°F before you start feeding it any nitrogen; dramatic damage to the plants is possible otherwise.

As a rule of thumb, it’s best to fertilize your yard every 8 weeks with the exception of the cold season (starting after the first frost hits). The intensity of nitrogen fertilization should be lowered during the cold months and maximized in June through September for most settings.

The Key to Fertilizing St Augustine Grass

St. Augustine friendly fertilizers come in all kinds of formulas and formulations. These can be synthetic or organic, all-purpose or specialized, liquid or granular – your lawn will benefit from them provided that they have a safe yet efficient nutrient makeup and are easy to apply according to the schedule. Simple Lawn Solutions’ 3-18-18 Lawn Food is my personal favorite for this grass variety because it meets all the criteria.

Have you encountered any problems with your St. Augustine grass so far? You’re welcome to share in the comments!

Bryan Mckenzie

Bryan Mckenzie

Hi there — my name is Bryan McKenzie. Before I’d got into gardening, I worked as a landscape designer at landscape design and consultation company in Jacksonville. I enjoy sharing the vast gardening experience I’ve accumulated throughout the years with like-minded green thumbs. Read more about me and my wife.

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