St. Augustine grass is an excellent type of warm-season turfgrass because it grows well even in sweltering and humid climates and looks fantastic when it’s well-maintained.
However, if your St. Augustine lawn is looking brown, dry, patchy, or, well, dead, reviving it and fixing those dead spots is often tricky–but certainly not impossible.
Not to worry, though, as we’ve got everything you need to know to get your grass lawn looking great again here.
Reviving fully dead grass is not viable, but it’s possible to repair it if it’s just damaged or starting to die off. Depending on the cause, you’ll need to potentially treat fungi, weeds, and insects and then fill in any bare spots. Proper maintenance will prevent the grass from dying again later.
Read on to determine why your St. Augustine grass is dying off and learn how to repair and revive it.
We’ll also go over maintaining it properly once you’ve got things starting to look green and healthy again.
Table of Contents
What Causes St. Augustine Grass to Turn Brown?
Before we get into the specifics of reviving and repairing your lawn, it’s best to go over some of the critical causes of damage to St. Augustine grass in particular.
Additionally, it’ll help to determine whether or not your lawn is damaged, dying, entirely dead and irreparable, or simply temporarily dormant for the winter.
If you’re seeing yellow and brown grass during the winter months only for it to come back in full swing in the spring, there’s a chance your lawn is simply going into dormancy for the winter.
When St. Augustine grass turns light green, it’s a different issue; click the link to learn more in our guide.
This is common with warm-season grasses, as they thrive well in the spring and summer but not so much in the fall and winter, even in hot and mild climates.
However, if your lawn is looking awful year-round, even during its active growth period in the spring and summer, you likely have a deeper problem killing off your St. Augustine grass.
Some of the most common culprits are the following:
- Brown patch disease, a lawn fungus to which St. Augustine grass is specifically vulnerable
- Gray leaf spot fungi (also particularly damaging to St. Augustine)
- Pest infestations, most often chinch bugs, armyworms, mole crickets, webworms, and spittlebugs
- Root rot
- Improper fertilizer use or fertilizer “burn” from using products with an unsuitable NPK ratio
- Poor soil quality
- Severe droughts
- Other lawn diseases and fungi
- Excessive shade/not enough sunlight
Treatments for these issues often vary, but even if you aren’t yet sure what exactly is causing your grass to die off, you’ll likely be able to repair it, at least to some degree, with a bit better maintenance.
We’ll get into these repair methods soon, but we’ll discuss how to pinpoint dying grass patches next.
It’s also worth noting if your grass is entirely dead, you likely won’t be able to bring it back to life.
Dying and damaged grass is one thing, but completely dead grass will need to be replaced with seed, sod, or plugs.
How to Tell if Your St. Augustine is Dying
There are a few key ways to tell if your St. Augustine grass is damaged and beginning to die off rather than merely being dormant.
If your lawn is looking dry, brown, and brittle during the spring and summer months, you’ve likely got more issues than mere temporary winter dormancy would suggest.
Fungal infestations like the dreaded brown patch do exactly what they say on the tin, essentially: they turn patches of your lawn brown, dry, and gross-looking.
Lawn fungi and diseases are some of the most common killers of grasses like St. Augustine.
The grass blades usually merely look yellow and wilted in their early stages, but the infestations progress quickly.
Your thatch layer will give you a good idea if your grass can get the nutrients and sunlight it needs to thrive.
Thatch is simply a layer of organic material, both dead and living, like:
- Grass Clippings
- Soil
- Leaf Litter
- Stems
- Microorganisms
- Other Plant Matter
Over time, this layer builds up and suffocates your lawn slowly, blocking it from taking in nutrients, water, and sunlight.
Dethatching whenever your thatch layer exceeds 1/4″ inches is ideal to combat this.
Unhealthy St. Augustine grass also tends to have excess weed growth and an abundance of common pests like the insects we mentioned earlier.
If you’re seeing more weeds than grass and bugs munching on the grass blades, you’ve likely got an issue with weeds, insect pests, or both.
More than anything, though, you’ll notice your lawn’s signature St. Augustine green color will be absent in certain areas or, in severe cases, throughout the entire lawn.
The sort of good thing about dying grass is even a total amateur can spot it, as the dead patches make themselves known pretty quickly.
Can You Revive Dead St. Augustine Grass?
It is possible to revive damaged or dying St. Augustine grass, provided the damage isn’t so extensive the grass has completely wilted and turned brown.
Completely dead grass is a lot trickier to repair, though, and it usually needs to be replaced with either new seed, sod, or grass plugs.
Before you head up to your lawn and garden shop to start from scratch, though, it’s worth at least attempting to treat it and bring back what you’re able to.
Grass, including St. Augustine, usually doesn’t die off altogether in one fell swoop–it dies in patches somewhat gradually, so there’s a good chance some areas won’t need to be fully replaced, even if things are looking grim.
To determine if you’ll be able to revive your St. Augustine grass or if you’ll need to completely replace specific patches, it will help to conduct a few troubleshooting measures to rule out as many culprits as possible.
These include:
- Poor soil quality
- Fungal diseases
- Fertilizer burn
- Root rot and more
Check Your Soil Quality
Having the right soil quality is crucial to the growth of all turf grasses, and testing your soil will tell you if the pH level is to blame or if the culprit is something else entirely.
Test your soil sometime in the spring if possible. St. Augustine grass fares best in fairly acidic soil with a pH level of around 6.0 to 6.5.
If your soil’s pH level is off, there’s a good chance this is at least partially to blame for your grass dying off.
Adjust the pH by either lowering it with aluminum sulfate, sulfuric acid, or elemental sulfur or raising it with agricultural lime.
Apply Fungicides, Herbicides, and/or Pesticides
Various fungal diseases, weeds, and insect pests are among the most common causes of dead St. Augustine grass (and turf grasses in general).
You’ll need to confirm or deny the presence of each of them to determine how to treat the issue moving forward.
With most insect pests, you’ll be able to do a simple visual check for the presence of, for example, chinch bugs or armyworms.
If you aren’t sure what certain pests look like, take a few photos of them and ask a lawn expert for their opinion or compare the pictures to others online.
From there, you’ll be able to find the right treatment for your lawn’s specific insect invaders.
It’s also possible to do a visual analysis for fungal diseases and weeds, but it’s a bit more tricky than differentiating between insect pests.
Brown patch is one of the most common fungal issues affecting St. Augustine grass in particular, and it’s also one of the most easily identifiable, as it simply presents as large, irregularly-shaped brown spots of grass throughout your lawn.
Treat this and many other common lawn fungi with something like this fungicide spray from BioAdvanced.
Weeds are also a notable threat to St. Augustine grass.
This particular variety of grass spreads via both stolons and rhizomes, so it spreads aggressively and quickly, but it’s still vulnerable to several common weeds.
Crabgrass is one of the most well-known weeds which targets St. Augustine in particular, though others like dollarweed, chickweed, and white clover are also common.
To treat weeds that have already established themselves in your yard, use a post-emergent herbicide with Atrazine.
Something like this herbicide by Southern Ag will work well for most common weeds.
After you’ve eliminated the weeds, treat your lawn with a pre-emergent herbicide every year during early to mid-spring to keep them from returning.
Apply the Right Fertilizer (But Don’t Over-Fertilize!)
Once you’ve determined whether or not your lawn has any insect pests, fungal diseases, or weeds and have treated them, it’s essential to ensure you’re using the right type of fertilizer for your lawn.
Using a fertilizer with the right NPK (nitrogen, phosphorus, and potassium) ratio for St. Augustine grass will promote healthy growth and regrowth after treating the main cause of your lawn’s deterioration.
Alternatively, there’s also a chance using the wrong fertilizer was the main reason why your grass was dying off!
Either way, it’s essential to know you’re applying the right ratio and amount of nutrients to your lawn.
In particular, for St. Augustine grass, something high in nitrogen is usually recommended.
A fertilizer with about a 3-1-2 or 16-4-8 NPK ratio will work well.
This fertilizer by Simple Lawn Solutions is an inexpensive and effective choice.
Apply fertilizer to your lawn in the spring after it comes out of its dormant stage and turns green again and then again around two months later in the early-to-mid-summer.
This will help revive any patches still looking a bit worse for wear and maintain the healthier spots to ensure they don’t start to wilt.
Adjust Your Watering Schedule
Another potential reason why your St. Augustine grass isn’t doing so well is your watering schedule and how much you’re watering your lawn each session.
Watering too often or too much will cause fungal diseases to take hold while watering too little will cause your lawn to dry out quickly.
This grass generally requires 3/4″ to 1″ inch of water per week during spring and summer and 1/2″ inch of water per week during the fall and winter.
Water the grass whenever it looks and feels dry.
If it looks and feels soggy or squishy, hold off for a bit to give your lawn the chance to absorb the water.
Stick to watering your lawn early in the morning, or around 10 AM or so, before temperatures become very hot.
This will ensure your lawn gets to take in enough water before the water starts to evaporate in the sun.
If you were previously watering your lawn too often or too little, adjusting your watering schedule and amount as detailed here will help repair any damage and properly maintain it while it heals and grows.
Aerate and Dethatch Often
Frequent aeration and dethatching are also crucial when it comes to maintaining a healthy, attractive St. Augustine lawn in addition to reviving a dying or damaged property.
Both practices help to improve the rate at which your grass can absorb nutrients, water, and sunlight by making the soil less compacted, though they differ slightly in execution.
There are a few different types of aeration, from core aeration, in which “cores” of grass and soil are removed and dumped on top of the lawn’s surface, to spike aeration, in which spikes are driven into the soil.
The goal here is to free up more space in the soil, so it isn’t as tightly packed.
On the other hand, dethatching involves removing the top layer of thatch from your lawn.
Thatch is merely a layer of living and dead organic matter, including:
- Stems
- Leaves
- Roots
- Grass clippings
- Microorganisms
This layer gradually accumulates atop your lawn, and sort of suffocates it by preventing sunlight and water from being absorbed.
There are also a few different dethatching methods, from manual rakes to liquid products, which break down the thatch layer.
It’s a good idea to dethatch your lawn when you notice the thatch layer exceeds 1/4″ inches thick.
By improving the soil’s aeration, you’ll be able to ensure the dying or damaged parts of your lawn are better able to access and take in the nutrients they need to thrive.
Maintain the Correct Mowing Height
Keeping your lawn mowed to the correct height is another great way to help treat damaged grass and prevent your yard from sustaining additional damage from the elements.
If your lawn becomes too overgrown, you’ll encounter issues with the grass being unable to absorb enough sunlight and nutrients.
If you trim it too short, you leave it extremely vulnerable to harmful, rapidly spreading lawn diseases and pests.
The ideal mowing height for St. Augustine grass is around 2 to 2.5″ inches.
This is a bit on the taller side, but this type of grass tolerates shade pretty well.
Learn more about St. Agustine grass growing in shade and other related questions in our article here.
Fill in Remaining Bare Spots with Sod or Plugs
If only specific patches of your lawn are dying off, you’ll be able to simply replace those affected areas with some sod or grass plugs!
Keep in mind, you’ll still need to keep up with maintaining your lawn, as we detailed above, to prevent the dying spots from spreading or returning.
But this is a great way to fill in those spots quickly and easily, especially if you don’t feel like re-seeding and waiting weeks and weeks for it to sprout and grow back.
To fill those spots with sod or plugs, first, get rid of the dead grass and rake up the soil.
Apply a bit of fertilizer to the area, water it, and then plop the sod or plugs on top.
Make sure you water the spots every day for the first week or two, and then resume your usual watering schedule.
Though you’ll technically be able to install sod or plugs any time of year, the success rates are far higher during the active growing season in the spring and summer.
Be sure to maintain these areas consistently via aeration, watering, fertilizing, and mowing to prevent your grass from dying off again.
Knowing When to Start Over With St. Augustine Grass
If your lawn is well and truly dead and beyond the point of no return, you’ll need to start over entirely with new seed, sod, and/or plugs.
This is disappointing, to be sure, but in some severe cases, it just isn’t possible to reverse the damage and bring your lawn back from the dead.
If the damage is far worse than just filling in a few bare spots here and there, you’ll likely need to remove the dead grass completely and replant new grass seed or buy a whole lot of sod or plugs.
Your choice will depend on your budget and how much time and effort you’re willing to put into reviving your nice, green lawn.
While grass seeds are cheaper, they take longer to grow, fill in, and take more effort to nurture.
Sod and plugs are more expensive, but they look great right away and don’t take nearly as much work to get growing.