Dethatching and Reel Mowing: How To Bring Your (Old) Zoysia Back to Life

On Oahu, common zoysia grass (properly known as emerald zoysia) is often found in landscapes, especially in Kailua and Kaneohe.  This grass is popular here because it is resistant to drought and salt, which makes it perfect for ocean front landscaping.

When maintained correctly zoysia is a beautiful choice, it is kept low and tight and has the look and feel of a golf course putting green.

But there are pros and cons to everything, and the main drawback to zoysia is that it can grow out of control quickly.  You’ve probably seen it before, where the grass clumps over itself into mounds like the photo below:


It’s pretty to some, if level footing isn’t important

This can make your yard uneven, hard to walk on and makes mowing difficult or impossible.


If your zoysia lawn has gone haywire, dethatching is best way to bring it back into order.

Thatch is the layer of old clippings and roots which accumulates between the actively growing turf above and the soil below.  Some thatch is normal and even healthy for turf.  But once it gets too thick it can harbor fungus, and other pests that can damage your lawn and other plants.

Dethatching is needed more for high-maintenance turf than low-maintenance turf.  As you may have guessed, zoysia falls under the “high-maintenance” category.  To keep it in good condition zoysia will usually need to be dethatched once every year or two.  Other types of grass may need to be dethatched rarely and sometimes never, depending on overall conditions.

Here is a zoysia lawn immediately after a dethatching, and two months later with watering and topdressing:


Zoysia immediately following dethatching


Two months later with a topdressing and watering program.

Dethatching is a tough job, so you need to decide if you have the time to do it yourself or if you will hire a landscape contractor like us to help you.

When dethatching zoysia, you want to take the grass down nearly all the way to the soil or sand (zoysia is often found in sandy yards, it grows there better than most varieties).  For small areas, this can be done with a mower and weed-eater.  For larger yards, a dethatcher may be necessary.  You can rent this machine from most equipment rental companies.

Once you have the turf back into the correct shape and height, there are a few things you must do to avoid a relapse:

  1. Topdress:  Topdressing with a layer of fresh new soil is highly recommended.  Soil will erode and settle over time, so it is critical to add fresh organic material and nutrients.
  1. Water:  As with all turf, regular watering is necessary to bring your zoysia back to life.
  1. Reel Mowing:  This may be the most important step for keeping your zoysia in shape.  A reel mower is different from a rotary mower, and is critical to maintaining zoysia correctly.  The photo below is an example of a reel mower, and the process is explained further below.

Notice the cylindrical blade is different than your typical “rotary” mower.

Regular Mowing

This point is so crucial that it warrants further explanation.  Zoysia grass needs to be cut more regularly than most other varieties.  It should be cut once per week, and no less than once every two weeks.

This can be tricky because zoysia needs to be cut even when it looks like it has barely grown or not grown at all.  It needs to be kept low, at almost ground height.  When it begins to grow up in height, this is where the clumping and fungus begin to appear again.  And it doesn’t take long for all that hard work to quickly overgrow.

If you would like to ask questions or get some pointers on your zoysia or dethatching project please feel free to contact us here.  We’d be happy to walk your property with you or chat over the phone.

Do you have any zoysia love stories or horror stories?  Please leave a comment below!  And feel free to share with any friends who may find this information valuable.

4 Responses to Dethatching and Reel Mowing: How To Bring Your (Old) Zoysia Back to Life

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  • Gabriella Cooper says:

    Hi, I have a very small area (about 5×15) planted with emerald zoysia. It looks beautiful right now, about 4 inches long in places. I want it to mound/clump and look more like the asian lawns and it’s well on it’s way to looking like that. I am reluctant to mow it because it would flatten it all to look like a putting green. Not at all the look I am after. But, I have read all about the thatching issue and it sounds like mowing is needed eventually. Or, is it enough to rake it from time to time to de-thatch? If I have to mow it, can I use a weedeater? I don’t have a reel mower.

  • Sam Wilhoite says:

    Aloha Gabriella!

    Thanks for your comment and questions. The main issue here is that my answer is almost too long for a comment, I should almost write another blog post! I will do that soon, thanks for the idea 😉 But for now, I’ll try give a short version…

    The difference between the two different looks you’re describing is that it is basically an all or nothing choice, you should commit to one or the other because the middle ground is usually unattractive!

    If you want the clump and mound look of the classic Japanese gardens, you won’t end up mowing it at all, ever. You will just let it grow and grow knowing that it will be a long process, and trim it periodically with a weedwhacker to keep the shape. If you continue to mow it, it will ruin the clumpy look you are going for.

    I actually love the bumpy look, just like the first photo at the top of this article, it’s beautiful! It just has to suit your personal taste and practicality, and it sounds like you have the perfect place for it.

    So yes, you will have a thatch issue, but that’s okay because in this case you just live with it for prettiness sake. What dethatching actually does is to remove basically all the grass and leave only the root system to grow back. Once you do that, you lose that mounded look that will most likely take you years to develop and grow.

    I hope that helps, and feel free to ask any more questions if they come up! You can also email or call me through the Contact tab at the top of this page if you would like help with more long winded explanations such as this one, haha!


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