Can You Dethatch St. Augustine Grass? (Risks and Precautions )

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The topic of dethatching St. Augustine grass is controversial, with the practice even considered highly risky.

The thick, sensitive warm-season grass that forms a carpet-like appearance requires proper maintenance practices, so can you dethatch St. Augustine grass?

Generally, St. Augustine grass rarely needs to be dethatched because its thick and slightly woody stolons push through the thatch, so the grass doesn’t choke. However, you must take action if the thatch grows to about an inch or longer.

If you deem dethatching St. Augustine grass necessary, do it properly with the right tools to avoid damaging your grass.

Continue reading this post to discover why, when, and how to dethatch your St. Augustine grass.

Can You Dethatch St. Augustine Grass?


how to dethatch st augustine grass

Yes, you can dethatch St. Augustine grass if the thatch build-up is about an inch thick or more. However, it would be best to take cautionary measures to protect your grass from damage.

While minimal thatch is beneficial to your lawn, a thicker layer is destructive as it restricts the roots’ intake of nutrients, water, and oxygen needed for proper growth and health of the grass.

Also read: Pros and Cons of Dethatching Lawn

In addition, thick thatch in St. Augustine grass impairs root development by preventing the grass’ above ground runners from sending new roots deep into the soil to kick-start growth. This slows down the spread of the grass and takes much longer for you to have a fully covered lawn.

Before dethatching your St. Augustine grass, you must ascertain that it’s necessary. Do so by doing the following:

  • Dig up a portion of your grass with a hand shovel-let the section’s dimensions be 3 inches long, 3 inches wide and 3 inches deep.
  • Measure the thatch thickness using a tape measure or ruler on the grass section you dug up.
  • If the thatch is ½ inch thick or less, don’t dethatch, but you will need to get rid of it if it’s more.

What Causes Thatch In St. Augustine Grass?

Considering St. Augustine grass isn’t prone to thatch, its occurrence results from a specific cause that you must uncover and rectify. Below are the causes of thatch in St. Augustine grass before dethatching.

1. Overfertilization

Fertilizers stimulate grass growth, but you wouldn’t want your grass to grow excessively fast within the shortest time.

Applying too much Nitrogen-based fertilizer to your St. Augustine grass or using it frequently causes excessive growth overwhelming the natural breakdown.

Read more: Grass Turning Yellow After Fertilizing

Moreover, rapid growth means you have to mow your grass more frequently to keep it short, leaving more grass clipping on your lawn’s base.

The decomposition rate of these clippings will be slower than the speed at which they are added to the turf, leading to thatch build-up.

In addition, some sources of nitrogen increase the soil’s acidity, encouraging thatching.

2. Overwatering

While your St. Augustine grass requires moisture, overwatering it can be problematic as it can cause thatch build-up. Excessively watering your lawn inhibits the organisms in the soil from breaking the thatch down, causing it to build up.

Overwatering the lawn also causes it to grow faster, meaning you will have to mow it more often. This will cause the accumulation of grass clippings that won’t decompose fast enough, causing your lawn to have excessive thatch.

3. Insufficient Moisture

Thatch decomposes more rapidly under wet conditions. Keeping your lawn dry slows down the breakdown of thatch, resulting in a faster build-up than decomposition.

Therefore, you need to maintain proper lawn watering to prevent thatching in your St. Augustine grass.

4. Not Mowing Regularly

Regularly cutting your St. Augustine grass reduces the amount of grass clippings with each mowing session because you won’t be removing 1/3 of the grass’s height. Small clippings will quickly decompose, turning into nutrients instead of causing thatch build-up.

When mowing your lawn, ensure you distribute the grass clippings uniformly and ensure they don’t accumulate in clumps. This means having an excellent lawnmower that doesn’t leave clumps.

5. Poor Aeration

Your St. Augustine grass will be at risk of thatching if the soil isn’t receiving sufficient oxygen because it will inhibit thatch-breaking microorganisms from multiplying and thriving. This is why lawn aeration is critical.

Why You Need To Get Rid Of Thatch In St. Augustine Grass

Excess thatch is problematic to St. Augustine grass since it irritates it and even damages your grass. The thick layer of living and dead plant material blocks oxygen, moisture, and nutrients from reaching the roots, starving the grass.

If thatch accumulates for an extended period, it could destroy the soil and grass. In addition, it provides a nesting spot for insects and encourages the breeding of pests like mosquitoes.

Therefore, it’s essential to remove excess thatch for the health and proper growth of your St. Augustine grass.

When To Dethatch St. Augustine Grass?

The best time to dethatch your St. Augustine is when it’s actively growing, which is in mid to late spring after the dormancy period is over.

Dethatching this grass in spring gives the lawn ample time to recover since the active growth period lasts until summer.

The spring’s vigorous growth helps your grass grow to the ideal height for mowing, which is crucial because you need to cut your grass before dethatching.

It’s not recommended to dethatch St. Augustine grass in fall because the warm-season grass will have a tough time recovering during this cool season. Choosing to dethatch in the fall will likely cause bare and dead spots in your yard.

The frequency you will need to dethatch St. Augustine grass will depend on how well you care for your lawn. Eliminating the causes of thatch like overwatering, overfertilization, and mowing too frequently will significantly help keep the thatch minimal.

How To Dethatch St. Augustine Grass

Before Dethatching St. Augustine grass, you must cut the grass blades at 2 inches to ensure the dethatching tool has sufficient access without destroying the stolons.

You will also have to water your grass 24 hours before dethatching to soften the soil and lower the stress on your grass.


Remember, the ground only has to be moist and not saturated, so don’t overwater. Moreover, St. Augustine is a sod-forming grass without rhizomes, so removing the top growth that it relies on to spread and fill the soil, leaving no bare patch, is detrimental to your lawn.

Therefore, to avoid damaging St. Augustine grass, you cannot dethatch with a power dethatcher. Instead, use a vertical mower or a hand rake.

Now that the preparation is over, it’s time to dethatch your St. Augustine grass. I’ll walk you through how to do it with a hand rake and a vertical mower.

How to use a thatch rake on St Augustine grass

Here’s how you can use a thatch rake to dethatch St. Augustine grass:

Step 1: Choose the right time to dethatch your lawn. The best time to do this is in the spring or fall when the grass is actively growing.

Step 2. Adjust the blades of your thatch rake to the appropriate depth. Most thatch rakes have adjustable blades that can be set to a depth of around 1/4 to 1/2 inch. This will ensure that you remove the thatch layer without damaging the roots of the grass.

Step 3. Begin raking the lawn in one direction, using long sweeping motions. Start at one end of the lawn and work your way across, making sure to overlap each pass slightly to ensure that you cover the entire area.

Step 4. Once you have finished raking in one direction, turn the rake around and rake the lawn in the opposite direction. This will help to loosen and remove any remaining thatch.

Step 5. Use a leaf rake to gather up the thatch and other debris that you have removed from the lawn. Dispose of it in a compost pile or other appropriate location.

Dethatching With A Vertical Mower

The process of dethatching with a vertical mower is also known as verticutting. IT involves passing a vertical mower (set to have the blades 3 inches apart) over the grass only once.

Make sure you don’t pass the tool over a spot two times to prevent lawn damage. Use a hand rake to pile the loose thatch once you finish dethatching, then collect and dispose of it.

A verticutter or vertical mower looks like a traditional lawnmower, but the single, horizontal blade is replaced with multiple vertical prongs, tines, or blades.

Dethatching With Liquid products

Dethatching with liquid product you’re basically energizing soil microbes that feed on organic materials to reduce thatch efficiently. Most of these dethatch liquids have molasses in them so they give these micro organism food to eat through that thatch layer.

You can incorporate this like once per month into your routine in spring and summer and you should see an improvement along with the correct mowing height.

Liquid dethatch products I recommend that you can use to dethatch St. Augustine:

After Dethatching Care

After dethatching your St. Augustine grass, aerate your yard with a core aerator to loosen the soil and speed up the recovery of your lawn.

The best time for aeration is after dethatching, so plan for the two lawn care practices together.

Moreover, apply a slow-release fertilizer with nitrogen, potassium, and phosphorus to boost growth. The fertilizer will have an easier time being absorbed now that you have removed the thatch.

Your lawn is also susceptible to weeds after dethatching because of the exposed soil, so consider applying pre-emergent weed killer to prevent the germination of weed seeds.

Your St. Augustine grass will also need adequate moisture after dethatching to boost recovery. Therefore, keep your regular watering schedule, but consider irrigating longer or reducing the hours between each session.


So, can you dethatch St. Augustine grass?

Yes, you can dethatch St. Augustine grass.  The best time to dethatch your St. Augustine lawn is when it’s actively growing, which is in mid to late spring after the dormancy period is over for faster recovery.

Thatch won’t be an issue if you take care of your St. Augustine grass. Therefore, be proactive by ensuring your lawn is watered and fertilized correctly, mowed correctly and regularly, and well-aerated.

A little thatch is beneficial, but the excess build-up will hurt your St. Augustine grass. When dethatching your lawn, choose the right tool, avoid a power rake and do it correctly.


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