Can you Dethatch St. Augustine grass?

St. Augustine is a warm-season lawn grass that is thick and carpet-like that can stay green all-year-round in warmer climates. It’s a very sensitive type of grass that’s why it’s important to know how to dethatch St. Augustine grass.

But is it possible to dethatch St. Augustine grass? Most people say you shouldn’t dethatch St. Augustine grass because it’s a sod-forming grass that doesn’t have rhizomes so if you use a power dethatcher you can end up removing most of the top growth that spreads and fills the soil’s bare patches. However, you can use a hand rake but wait till your lawn is actively growing so it doesn’t hurt the stolons. Once your St. Augustine grass has grown enough to be mowed, you can dethatch it in mid to late spring.

Thatch and St. Augustine

Thatch is a layer of dead plant material that accumulates on the topsoil that is caused by excess mow clippings, leaves, and other debris settling on your lawn. A problematic layer of thatch takes years to build on your lawn. 

Here is a good video about thatching.

If the thatch on your lawn is below ½ an inch, it’s beneficial for your lawn because it helps to retain moisture and as the leaves decompose they return their nutrients into the soil.

Thatch can only break down if you have a healthy and properly cared for a lawn that is warm, moist, and aerated.

It can also cause moisture problems in the soil and make it hard for water to penetrate through leading to faster evaporation and your grass drying out even after watering it.

St. Augustine is a special lawn grass that grows horizontally along the surface with lots of above-ground stems that form a stiff firm mat over the soil that can easily get damaged by the sun.

The leaves grow upwards which protects the stems from the sun while the roots grow downward and the mat formed by the stems is often confused for thatch.

How to determine if Your Lawn needs Dethatching

If you notice water running off after watering without penetrating the grass, it’s a sign that it’s time to dethatch your lawn. Kneel on your lawn for a closer examination to check if there’s a layer of thatch underneath.

If you notice a layer of old, brownish gray grass stems that is packed together that is an inch above the soil surface, you’ll need to dethatch your lawn.

How to keep your thatch layer at a manageable height

  • Water your lawn deeply and infrequently at least once per week for about 45 minutes to 1 ½ hour. This will saturate your soil and keep the thatch moist to allow it to decompose.
  • Thatch will break down much faster if the grass clippings are smaller. Mowing your lawn twice a week with a mulching blade, but don’t cut more than 1/3 of the growth.
  • Aerating your lawn in the spring helps oxygen to penetrate the soil which provides food to the microorganisms which in turn breaks down the organic matter.
  • If you have just a few inches of thatch buildup, changing your lawn care practices can help to encourage faster decomposition and you might not even need to use a dethatcher after the growing season if you have a healthy lawn.
  • Vertical mowing can help keep your lawn healthy and remove dead vegetation by lifting it to the surface with the help of the blades on your vertical mower. the best time to do vertical mowing in early spring for warm-season grasses like St. Augustine grass before the grass greens up or when it’s actively growing, but not when it’s hot and the grass requires a lot of water to grow.

Dethatching tools and machines

There are different forms of dethatching tools and machines you can use from manual, electric, or gas-powered.

What they all have in common are the spinning pieces of metal that pierce and lift thatch from your lawn.

Using a hand rake to dethatch St. Augustine grass

Using a hand thatch rake is the best way of dethatching your lawn instead of using a power rake, but you have to wait till your lawn is actively growing.

  • Before you rake, make sure to irrigate your lawn the day before because it’s easier to dethatch when the clippings are wet. Mow your St. Augustine grass to about 2 inches to allow you easier access to the thatch. Although it’s too low for regular mowing, the grass will still recover.
  • Use the hand rake to pull the thatch layer up. If it easily comes up rake it into piles and removes it, but if it’s deep and compacted, rake up what you can and use your mower to go over your lawn then use a collection bag to pick up the clippings and loose thatch.
  • Remove all the thatch till you can see the soil and although it’s healthy to leave ½ inch of thatch on your lawn, it can be a hick and compacted layer that will not break down easily. So it’s best to remove most of the thatch and let a small layer form naturally.

Power dethatching

There are 2 machines you can use for dethatching, a power rake and a dethatcher.

A power rake is a more aggressive dethatching machine to use on your St. Augustine grass lawn than a dethatcher and it can most likely destroy your lawn so the best machine to use is a dethatcher.

It uses tines to pull the thatch up to the surface, it does less damage to the stolons and your lawn will recover faster.

A power rake will cut through the grass and soil to break the thick layer of thatch underneath.

It’s used to handle serious thatch, but it can damage your lawn because it can pull up living plants along with the dead grass.

If you have a large lawn, a power dethatcher is the best machine to use. You just run it in a pattern that will cover your entire lawn at once to make your work easier.

Always remember to mark where all hidden objects and irrigation heads on your lawn before using a power dethatcher to avoid damaging them.

Once you’re through your lawn will look terrible, but don’t worry that’s the way it’s supposed to look after dethatching.

What to do after dethatching

Dethatching puts a lot of stress on your lawn and the next few weeks after dethatching, your grass will try to recover and fill the bare spots on your lawn.

You can start some preventative maintenance practices and provide nutrients to your grass to help it recover.

  • Irrigate

A layer of thatch helps to prevent moisture from evaporating from the soil and now that you have removed that layer, water will evaporate quickly until the new grass fills the bare spots.

Your grass will also need more water than usual as it needs water to absorb fertilizer for the new growth.

Water infrequently but deeply but choose to either irrigate for longer or reduce the time between watering.

  • Fertilize

The thick layer of thatch has been acting as a blockage for nutrients to penetrate to the roots so most likely your lawn is starved.

Now that you’ve removed the thatch, your soil can absorb nutrients that your lawn needs for healthy growth.

Apply a slow-release fertilizer with equal parts of nitrogen, potassium, and phosphorous that will help your lawn begin to recover.

  • Improve the soil

A thatch buildup can cause the soil to get compacted which makes it hard for organic matter to break down easily and get incorporated with the topsoil.

After dethatching, get your soil tested at your local extension office.

Topdress your lawn with compost at the beginning and end of every growing season to improve the texture of your soil.

  • Treat the weeds

Having bare spots on your lawn will attract weeds, so immediately after dethatching don’t allow broadleaf weeds to take over your lawn.

Use a pre-emergent weed killer to prevent weed seeds from germinating and this will give your St. Augustine grass time to fill the bare spots.

  • Continue to mow

After dethatching continue to mow your lawn to encourage new grass growth. After dethatching, one of the major concerns is root growth and a healthy lawn will need healthy root growth to flourish.

Continuing to mow your lawn after every 4-5 days and gradually work your way to a mowing height of 4 inches to encourage new growth.

Benefits of dethatching

To ensure that you have a healthy lawn after the winter season, it’s important to expose the soil to sunlight and warmth.

By dethatching your air can circulate into the roots and provide carbon dioxide needed by the existing roots and new root growth.

  • Ensures your lawn has enough nutrients

Thatch is a layer of organic matter that isn’t essential to the health of your lawn.

Its decomposing plant matter that can deny your lawn essential nutrients and dethatching will allow you to remove this organic matter and open up your lawn for nutrients.

  • Improve the health of your soil

Thatch prevents essential nutrients, air, and water from reaching your soil. Your grass can still grow, but it won’t have a healthy growth.

Dethatching will help to improve the health of your lawn to allow water, direct sunlight, and air to get into the soil. It also helps fertilizer to work more efficiently and spread in the soil to ensure a thick and healthy lawn.

  • Allow air and water into the soil

For your lawn to grow properly, it has to have access to enough water and air, and because it’s a living thing air and water is necessary for its growth.

If your lawn has thatch more than an inch thick, you’ll not have a healthy growing lawn.

  • Allow fertilizer to reach the soil

If you’re applying fertilizer to your lawn that is full of thatch, chances are it will not reach the soil and serve its purpose.

The only way to ensure that the fertilizer reaches the soil and spreads evenly into the soil is to dethatch your lawn.

This will improve the health of the roots to ensure your lawn grows beautifully.

  • Increase your lawn’s beauty

As a homeowner, there’s nothing more beautiful than having a healthy lawn.

Although a little thatch can be beneficial, too much can give you an uneven lawn. An uneven lawn will remain uneven even after mowing.

Dethatching will remove all plant matter and dead grass that is causing your lawn to lose its shape and beauty.

When to dethatch different lawn grass types

Warm-season and cool-season grasses grow actively at different times of the year so the ideal time for dethatching your lawn will vary.

That’s why it’s important to know the kind of grass you’re growing on your lawn.

Lawn grass type

Grass-type

When to dethatch

Warm-season grasses

Bermudagrass, Bahiagrass, centipede grass, Zoysia grass, St. Augustine grass. Buffalo grass( doesn’t usually develop thatch)

In areas with frost and occasional snow, the best time to dethatch is in late spring to early summer before the heat arrives and your lawn needs a lot of water.

In the warmest areas, it’s best to dethatch in early spring, but wait till the grass is actively growing

Cool-season grasses

Kentucky bluegrass, rough bluegrass, creeping bentgrass. Tall, red, hard, chewings fescue and ryegrass rarely need thatching

Dethatch in early spring after the grass is actively growing and you’ve mowed it once or twice. Also in early fall to give the grass time to grow before the cold weather.

Final thoughts

Thatch is not a bad thing to have on your lawn and it’s necessary for St. Augustine grass, but if you think your lawn needs to be dethatched you should use the necessary tools or machinery needs to ensure you don’t cause permanent damage to your lawn.

Also read

How to Make St. Augustine Grass Spread Quickly

How Do You Revive St. Augustine Grass

Centipede vs St. Augustine – Pro’s and Cons

Sources and References

Solving Extreme Thatching In St Augustine Lawns

Maintaining St. Augustinegrass Lawns

Thatch and Its Control in Florida Lawns

Thatch Prevention and Control

St Augustine – Dethatching

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