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If your lawn is feeling a little spongy or if you’ve noticed a thick layer of grass blades and other material building up, it might be time to dethatch your lawn. 

A thin thatch layer is beneficial most of the time, but excessive thatch has its risks.

What is dethatching? It’s the process of removing organic matter build-up (“thatch”) on your lawn. Excess thatch could impact the long-term health of your turf.

How to dethatch a lawn? The easiest way is to use a dethatching rake to break up the grass clippings and other dead plant material under the grass. Alternatively, you can “scalp” your grass with a lawn mower or hire a power rake. And remember – you only need to dethatch warm-season grasses!

Noticed too much thatch? Keep your grass healthy by learning what dethatching is and how to dethatch your lawn.


What is Lawn Thatch? What is Dethatching?

Lawn thatch is a layer of dead plant material such as grass. 

It forms between the soil and grass roots, often resulting in thatch buildup. If you’ve got a thick thatch layer on your lawn, it feels a bit spongy when walking on it.

Dethatching is the process of removing the thatch layer on your lawn. There are several methods, such as using a dethatching rake.


Benefits of Dethatching a Lawn

dethatching the lawn

Thatch buildup is a normal occurrence on many lawns. Dead grass and dead leaf material will naturally accumulate over time, especially if you mow your lawn regularly. A healthy lawn will break down thatch by itself.

However, older lawns or ones with thick thatch might not break down the dead vegetative material. This will impact the appearance of your lawn, and increase the risk of waterlogging or fungal diseases.

Dethatching allows air, water, and nutrients to reach the soil and feed your lawn grass. This results in a healthier lawn overall.

Other benefits of dethatching a lawn include:

  • Improved nutrient density
  • Better curb appeal
  • Increased root strength and growth
  • Retained moisture
  • Decreased water runoff
  • Healthier grass growth


How to Tell Your Lawn Needs Dethatching

One sign that your lawn needs dethatching is if you see dry patches and uneven growth after mowing. 

Other ways to tell if your lawn needs dethatching include:

  • Spongy or springy ground
  • Weak grass blades
  • Invasive weeds
  • Unhealthy grass (yellowed blades, etc.)
  • Presence of insects or fungal diseases

You can also measure the thatch layer, either by digging up a small sample of ground or sticking your finger/a ruler into the thatch. If the layer measures over 2.0cm, you’ll need to dethatch.


When to Dethatch Your Lawn in Australia

Green lawn with blue sky and clouds

It’s important to know that you should only dethatch warm-season grasses. Cool-season grasses do not respond well to dethatching, which may permanently damage your lawn.

Do not dethatch wet grass, as you could cause permanent damage to your turf.


What time of year to dethatch your lawn in Australia

It’s generally best to dethatch your lawn in Australia from late spring to early summer, or from late October to early December.

Lawn thatching in early spring means your lawn may take longer to recover, so you may have bare patches for a few weeks. You also risk weeds taking over, which will cause more problems.

Do not dethatch your lawn before it’s gone through its first summer.


How often to dethatch your lawn

There’s no real schedule for dethatching – it needs a more strategic approach. A moderate layer of thatch actually leads to healthy lawns.

This means that if you properly maintain your lawn, you may never need to dethatch it. Or maybe you’ll only need to do so every few years. It will depend on how much thatch builds up over time.


How to Dethatch Your Lawn

There are several ways for thatch removal, which will depend on the size of your lawn and what equipment you have available. Whichever method you choose, mow your lawn to half its normal height before dethatching.


1. Thatch rake

A lawn thatcher in a garden with yellow leaves on the grass.

The simplest method is using a manual dethatcher, or a thatch rake. Its short, curved tines will slash the thatch and pull it up from the soil surface. This is the most cost-efficient method, but it also requires the most effort.

Use for: Mild thatch problems (less than 2.5cm) and small lawns


2. Low-cut lawn mowing

Also called scalping, low-cut mowing involves setting your lawn mower to its lowest blade height. You can set it all the way down from the start, or gradually lower the blade until you’ve removed all the thatch.

Use for: Warm-season lawns with rhizomes, and mild to moderate thatch


3. Vertical mowers

There are several terms for this: vertical mowing, verticutting, or vertimowing. 

These specialised mowers have vertical discs that slice through the thatch into the soil. The discs dig deep and uproot thatch, and even level the lawn slightly.

It’s best to overseed or top dress your lawn after vertical mowing. Also, note that you may have to hire a professional to ensure a proper job.

Use for: Severe thatch or uneven lawns


4. Power rake

dethatching a lawn

A power rake is similar to a lawn mower, with steel tines (“flail blades”) on the bottom of the machine. Use the highest setting first to ensure you’re not pulling out the grass roots and damaging your lawn.

Use for: Large gardens and moderate to severe thatch


5. Lawn coring

This method is best for cool-season grasses, which don’t have rhizomes (runners) that help them regenerate. Coring or aeration involves punching out soil, thatch, and grass to leave holes in the soil surface.

Coring is not as effective as other methods, since it will not impact a heavy thatch layer.

Use for: Cool-season grasses or mild thatch


What to Do After Dethatching Your Lawn

Debris Left Over by an mechanical Lawn dethatcher

If you remove thatch, your lawn may look a little shaggy or unkempt since the process isn’t very gentle. 

After dethatching, water your lawn deeply and apply balanced fertiliser. You can also purchase some grass seed to overseed your lawn.


Why Thatch is Good in Moderation

A thin layer doesn’t automatically mean a thatch problem. 

There are ways that a layer of thatch can benefit your lawn. It can:

  • Act as natural mulch
  • Retain moisture for soil
  • Insulate the ground and roots
  • Provide traction for walking or running
  • Improve soil quality
  • Filter rainwater
  • Maintain uniform soil pH


What Causes Excess Thatch?

It’s natural for organic matter to build up on a lawn, but microbes should decompose the thatch layers over time. 

Too much thatch can be caused by:

  • Overwatering or too-frequent watering
  • High-nitrogen fertilisers
  • Infrequent lawn mowing
  • Too-compacted soil
  • Acidic or nutrient-poor soil
  • No earthworms due to pesticides


How to Prevent Thatch Buildup

A cool-season lawn is less likely to develop thatch, especially ryegrass or tall fescue. Kentucky bluegrass or creeping red fescue may develop some thatch.

Warm-season grasses are more prone to developing thatch, especially Zoysia and Bermuda. A Kikuyu lawn may also build up a thick layer.

To prevent thatch build-up, here are some lawn care practices:

  • Water your lawn deeply instead of frequently but shallow
  • Do not over-fertilise, especially with high-nitrogen formulas
  • Mow your lawn regularly (or get a mowing service!)
  • Avoid pesticides and fungicides that harm earthworms
  • Check on your thatch thickness


Proper Lawn Maintenance

It’s essential that you regularly mow your lawn (unless it’s rained – avoid mowing a wet lawn). You should know how often to mow and at what time, as well.

You might also want to assess your lawn and see if it needs levelling. An uneven lawn surface makes it difficult to maintain, and might lead to uncontrolled runoff or standing water.

Knowing what is dethatching and how to dethatch your lawn means you can maintain good grass health, for large lawns and small ones. 

Thankfully, though, you won’t need to deal with thatch as often as you need to mow and water – so don’t worry about adding another chore to your yard work every week!

About Author

Jamie Donovan

Jamie is an Australian horticulturalist and landscape designer. He enjoys writing about landscape architecture, garden design and lifestyle topics.


About Author

Jamie Donovan

Jamie is an Australian horticulturalist and landscape designer. He enjoys writing about landscape architecture, garden design and lifestyle topics.