Dethatching St Augustine Grass

St Augustine grass happens to be one of the most sensitive types of grass. That being the case, it’s important to know exactly how to dethatch St Augustine grass before you get started. If you’re wondering what thatch is please read our article What is Lawn Thatch? We’ve also written a general article on dethatching, Thatch Removal – Dethatching, which is also worth a read if you’re considering undertaking this lawn maintenance chore.

Specifically related to St Augustine you need to consider a few different variables.

How do I know its time to dethach my St. Augustine grass?
If you have more than a half an inch of thatch, or decomposed plant material, its time to dethatch.  If you examine your grass you should be able to determine if the grass is growing on soil or thatch.  If its that latter you know what to do.

Do I need special equipment for St Augustion grass dethatching?
Yes!  The power tool you rent to dethatch should have vertical blades.  Its also critical you find vertical blades that are adjustable left to right, so you can put at minimum of 3″ between the blades.  This ensure that the stolons aren’t cut permanently damaging your lawn.

When should I dethatch?
Only dethatch when your St Augustine is growing vigorously.  This is usually in the June to July time frame.

What should I do after I’m done dethatching?
Once you’re done dethathing give your lawn a healthy dose of fertilizer and water as its been traumatized and needs some extra nutrients to recover.

Now that the thatch has been removed your St Augstine grass should flourish.  All the restriction of air, water, and fertilizers are removed.  Get that lawn mower blade sharpened!


  1. I have St Augistine grass that, along with bermuda, has invaded and is attempting to take over my fescue in areas that are exposed to sunshine. I am in the Los Angeles area. I would love to find something that selectively kills bermuda and St Augistine grasses, but leaves the fescue alone. Unfortunately, I don’t believe such a chemical exists. If I am correct in this assumption, I would settle for just killing the St Augistines, and leaving the bermuda and fescue to battle it out! Is there anything that will help me in this effort?

  2. gary merrill says

    My super nice St Augstine yard had thatch was becoming brittle but still flurished,was always nice and green,lots of money and energy invested in this lawn.We live in Largo Fl; Super hard freeze turned every thing super brown,weeds are already taking over because neighbors donot care about their lawns.Please is there anything I can put on my yard to help it during this hard time it is in? PS It never freezes here for two weeks maybe more.

  3. Dan Turner says

    HELP! I have an invasion of chinch bugs that are destroying my beautiful St. Augustine lawn. I know it needs dethatched, but after that, what else might help in my battle against these bugs that chow down on St. Augustine?

    I also have large areas that have become totally invaded by Bermuda and am wondering the best way to get rid of the Bermuda without destroying the St. Augustine.

    • I have been using Scotts Summergaurd on my St Augustine for years. No cinch bugs at all. It is hard to find in the winter months. But Costco and Lowes carry it in the spring. Little expensive but it is excellent for St. Augustine. Just follow the directions on the package. Good Luck!

  4. for dan turner. i had same problem on the bermuda invade i tryed it and it work for me was * SCOTT BONUS S * IT kill the weeds and bermunda also made my lawn nice green and spred where the bermunda was.

  5. I have an area of my st Augustine lawn that has died and is matted. It’s about 20 by 20 ft in size. What is the best way to get the dead grass out and replace the area of the lawn?

  6. I live in the Los Angeles County, the San Fernando Valley. I have always had a great St. Augustine yard. This year with the water rationing, most of my St.Augustine has gotten brown and as been invaded with other grasses. There are areas that are dead and so thick and matted down. I have tried to hard rake out most of the dead areas (a lot!) but my gardener says that that thatching would help get rid of all the dead stuff and help bring the St. Augustine back. Is is really a big mess? and Can I expect the lush St. Augustine to return. The back is fabulous and green, and gets shade.

  7. I live in Orange County Ca, i had beautiful st augustine grass, until i spread weed killer. I went to a lawn care place who sold me the product. Ever since i used it it killed the weeds for the most part but it also damaged my lawn. It is now June/July and i see no growth. I want to dethach but since it’s not growing i’m afraid it will make it worse. Should i dethach even i see little to no growth? I’m thinking it could be poor drainage also my soil is very clay e. Your thoughts?

  8. John P Tatum says

    I’m not a fan of St Augustine. It has poor drought/freeze tolerance and requires a lot of water. Bermuda isn’t as attractive a lawn, but it has better drought and sun tolerance and requires less water. The drought two years ago severely damaged the St Augustine I inherited when I bought this house, as much as I don’t like it, it’s better than the assortment of weeds I has growing in its place. So now it’s onto encouraging the St Augustine to grow and choke out the weeds. I’ve tried introducing Bermuda. But with little money and knowledge I haven’t had much success.

    • I have had St. Augustine for many years. Keep it cut short. Feed it Scotts Summergaurd fertilizer three times a year. Dethach it about every five years and it will be the greenest grass on the street. Believe me!

  9. I have had St. Augustine grass for 30 years, I live in Orange County So. Ca. I ordered enough sod to cover my front yard approx. 40X50 sq ft. from a planter in LA county, had to rent a flatbed truck from Home Depot , get up at 3 in the morning to be there , they cut and loaded the sod on the truck at no extra charge. There was so many gardeners there doing the same thing. This is the best way to buy this sod, otherwise your gonna pay a fortune for it via a local garden store. This is the best grass (weed) I’ve ever had, it does become dormant durning the winter months (in CA, not really winter) but comes alive in march/april,, I fertilize it every year in late march with regular topper and a mixture of sand. I have never de-thatched , however, the last few years I,ve been having problems with what I call “stringers” , long shuts that appear especially after cutting. I finally go some professional advice and they recommended de-thatching! They guarantied that will solve the problem. T can rent the de-thatcher at the HD for 4 hours at a minimal fee so that is my new project come March next year. One other thing, most importantly, this grass saved my life last year, I was on my latter trimming a palm tree, probably 12/13 ft up the latter, latter tilted, I fell on my front lawn on the st Augustine grass, 4 inches thick like a 4 inch cushion, was uncounchious for a few seconds but if it wasn’t for this plush grass, who knows… My wife say me fall and called 911, I was up before they got there but learned a big lesson, no more latter for me!!!! Long story, but you are gonna love your St Augustine grass forever. last thing, it is a weed, but most weeds do not survive because it is so aggressive with the exception of nutgrass, it will find its way thru. If this happens, no problem , there is a product called “sedgeHammer”, mix a product “sprayMate” with it and it sticks to the nutgrass, walla, the nutgrass is gone!!! (it is the most difficult weed I ever had to deal with), hope this was informative for you, JohnnyDishes.

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