Floratam St. Augustine Grass

St. Augustine Grass Care & Maintenance Guide

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Written By: Mark Marino, a Massachusetts Core Applicator License holder
and owner/operator of Lawn Phix,

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A warm-season grass popular in sub-tropical climates like the Southern United States, St. Augustine grass is a spreading, low-growing grass with a vibrant green hue and broad, coarse leaf blades. St. Augustine grass forms dense mats and is well known for its terrific salt tolerance. Many property owners favor this grass for its low maintenance needs. This grass type also grows well in sandy soil and other soil types. Even though St. Augustine grass is not as fussy as some grass types, it does require some lawn care to support its health. 

St. Augustine Lawn Care Tips

To care for St. Augustine grass and achieve a healthy lawn during the growing season, rely on the following lawn care tips:

St. Augustine Grass Fertilization

It’s a good idea to fertilize your St. Augustine lawn. Plan to provide nitrogen fertilizer at one pound per 1,000 square feet of lawn. You should begin fertilizing your St. Augustine lawn about three weeks from the time the grass turns green. Follow a fertilization schedule, applying soluble nitrogen about every eight weeks. 

Although one pound per 1,000 square feet of soluble nitrogen is a rule of thumb for fertilizing St. Augustine Grass, you may want to conduct a soil test to determine if your soil is low on important nutrients such as phosphorus or micronutrients like calcium. Conduct a soil test in early spring to identify the ideal fertilizer for your lawn. A soil test will tell you if you need a high-potassium fertilizer or an iron supplement to achieve the lush lawn you crave. You can make fertilizer calculations based on the test. Tests generally need just a small soil sample to produce an accurate result.

During summer, you can apply a granular fertilizer of iron to grass; only take care because iron can stain your paved surfaces. By the end of summer, you can reduce your feed fertilizer schedule. At this time, you can switch to a high potassium fertilizer / low nitrogen fertilizer for your St. Augustine lawn.

Weed Control

Since St. Augustine grass grows in dense mats, it provides a natural defense against weeds. However, if your St. Augustine grass is struggling, weeds could infiltrate. To prevent weeds, apply a pre-emergent herbicide in early spring to help guard against broadleaf weeds, grassy weeds, or summer annual weeds. You may wish to apply a post-emergent herbicide to eradicate any existing weeds from your St. Augustine lawn grass. Remember to choose a pre-emergent herbicide for weed control that’s safe for St. Augustine lawns. Be sure the label says it’s a St. Augustine-safe herbicide before applying.

Also, many weeds can be prevented from infiltrating your lawn while it’s actively growing if it’s growing dense and healthy. A post-emergent herbicide may not be needed if your lawn grass is adequately protected with pre-emergent herbicides. Apply post-emergent herbicides if weeds appear in your grass.

Disease Control and Fungus Control

St. Augustine grass is vulnerable to some types of lawn diseases, especially downy mildew disease, making disease control an important consideration. To reduce the risk of lawn fungus overtaking your entire lawn, treat it as early as possible. Grass lawn diseases like gray leaf spot or brown patch can erupt in wet and humid conditions. Be sure to water your St. Augustine lawn infrequently and deeply to encourage a strong root system. You may also need a fungal treatment to prevent the disease from spreading.

Insect Control of St. Augustine Grass

Insect control measures are important for St. Augustine grass, which is vulnerable to chinch bugs. Chinch bugs are especially problematic for St. Augustine grass because they produce toxins that prevent grass roots from absorbing water properly. The result is the grass will die. Mole crickets can also be a problem for this type of grass. Keep an eye on your lawn to determine if insects are a problem. If so, you will need to apply an insecticide that’s safe for St. Augustine grass.

Mowing Schedule for Your Grass

Once your soil temperatures warm up and your grass emerges from its winter dormancy, you can begin to mow your St. Augustine grass. The ideal lawn height for St. Augustine grass is between 2.5 and 4 inches. You may wish to allow grass growing in shady areas to grow slightly taller. Be sure that your mower blades are sharp before mowing your lawn. Raise the mowing height by about half an inch if your lawn is suffering signs of drought stress or prevent drought stress during periods of little rainfall.

Watering St. Augustine Grass

St. Augustine grass needs more frequent watering to ensure healthy root growth during the spring growing season. It’s best to water your St. Augustine grass early in the morning. Avoid watering your lawn in the evening or during the hottest part of the day. Water your lawn grass deeply in the morning to promote strong root growth during the growing season. The root system of your grass will suffer if you water during the hottest part of the day because the water will evaporate before it reaches the lawn roots.

Warmer temperatures may necessitate more frequent watering of your St. Augustine lawn. New sod will also need more frequent irrigation. New grass should be watered in the morning to reduce the risk of fungus. Watering in the evening doesn’t allow the grass blades time to dry out. The grass can hold moisture too long, which makes it susceptible to lawn disease.

St. Augustine Lawns FAQs

How do I make my St. Augustine lawn grow thicker?

You can add St. Augustine new sod plugs to fill in bare patches of your lawn. To encourage a thick healthy lawn, adhere to your fertilizing schedule, watering schedule, and mowing schedule. You may also need to apply a pre emergent herbicide and fungicide to keep your lawn healthy. Weed control and insect control will help you keep your lawn thick and healthy. Consider an iron supplement during the warm temperatures of summer.

What kills St. Augustine grass?

A fungal disease like brown patch can kill St. Augustine grass. Chinch bugs and mole crickets can also seriously harm this type of lawn grass. Apply a fungicide treatment or insecticide treatment if your lawn starts to show signs of these problems.

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Author's Note: this piece has been updated for accuracy since its first publication on

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Author: Mark Marino
My name is Mark Marino, and I am the founder, owner, and operator of Lawn Phix. With a passion for lawn care and turf nutrition for over a decade, I've dedicated countless hours to correcting soil and perfecting lawns. Today, my expertise, backed by formal courses at UMass Extension Pesticide Education, allows me to offer top-tier lawn care services and advice. I am a fully licensed and insured lawn care applicator in Massachusetts, specializing in comprehensive turf nutrition, weed control, and lawn pest control. My license number is AL-0053865. Contact me at [email protected] or +1 (508) 500-8402.

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