Knowing how to dethatch a lawn can give you healthier grass all year round. Thatch is essentially a layer of dead plant matter and debris which gradually forms on the surface of the soil. It’s produced faster than it can break down, and so will grow thicker and thicker over time. If not removed once it reaches ½ inch in thickness, this layer will ultimately overcrowd the surface, reducing access to water, oxygen and the necessary nutrients grass needs to flourish. So if you want to keep your lawn healthy, thatch needs to be removed when necessary. Ignoring thatch is one of the many lawn care mistakes you could be making.
The trouble is, thatch is quite tricky to remove. It can be thicker than you imagine and can cover a wide area. Luckily, we’ve pulled together this useful guide to simplify the process. We will cover what to do and when to do it, answering any questions you may have along the way. Once you’re finished, your grass will be free to grow and flourish once again. Here’s how to dethatch a lawn.
How to dethatch a lawn
Power rake/electric dethatcher (optional)
Vertical mower/scarifier (optional)
Before you begin dethatching, check how thick the layer of thatch is — if it’s less than ½ inch, dethatching won’t be necessary. You can check this by digging up a small, concealed section of the grass and soil with a trowel and measuring the layer. A healthy layer of thatch is actually good for your lawn; it locks in moisture and insulates the soil. Plus the necessary water and air can still pass through.
1. Choose the right tool — If you choose the right tool for the job, the process will be a lot easier. An everyday rake can work for small lawns, but for the best effect, invest in a dedicated thatching rake, such as the Bully Tools 24-Tine Leaf and Thatching Rake ($59.99, Amazon (opens in new tab)). The long and sturdy tines on rakes such as these make them ideal for removing thatch.
If you’re dealing with a larger yard, another option is to use a power rake or an electric dethatcher. These look a lot like lawnmowers and work in a similar way — you push them along while the machine digs tines into the ground to remove and deposit the thatch. An example of this would be the Sun Joe AJ801E 12-Amp 13-Inch Electric Dethatcher and Scarifier ($174.99, Amazon (opens in new tab)). These machines are better suited if you’re dethatching a larger space. They can be rented from home department stores if your storage is limited.
Finally, there’s the option of using a vertical mower or scarifier. These should only be used on lawns which are suffering from an excessive build-up of thatch that can’t be removed otherwise. These devices are a last resort because they feature blades which will literally tear the thatch away, damaging any grass roots in the process. Electric dethatchers often double up as scarifiers, as the above recommendation demonstrates.
2. Mow your lawn — You’re going to want to mow your lawn down to about 2 inches in height before dethatching. This will help your tools effectively reach the thatch layer.
3. Get to work — If you’re using a rake, don a pair of the best gardening gloves (working gloves would be ideal) and prepare for some hard work. The motion isn’t exactly complicated — you’re literally going to use the rake just as you would when collecting leaves. Drop the tines onto the ground, making sure you pass through the grass blades to reach the thatch, and then pull back to rake it loose. This takes more effort than you’d think.
Our Audio Editor, Lee Dunkley, said ‘I started dethatching my lawn using a manual rake, thinking this should be quick and easy, however I got about ¼ of the way through the task and realized I needed to get the electric dethatcher out. This is far more taxing than you’d imagine.’
Because of this, we’d recommend using an electric dethatcher if you want to save time and energy, or if you suffer from back pain. You literally push these back and forth, much like a lawnmower, and it gives you the same finish. Some can even collect the thatch as you go, so you don’t need to collect it off the ground afterwards. You may need to make up to three passes to completely dethatch the lawn, and you should work perpendicularly with each pass for the best results. Make sure you mark and avoid any sprinkler heads or tree roots if you opt to use an electric method.
Vertical mowers or scarifiers work in the same way; you pass over the grass much like you would with a lawnmower. However, start on the highest setting with the first pass and then work your way down as necessary with subsequent passes. This will help loosen the thatch and will give your lawn as gentle a treatment as possible. If the above seems like a lot of work, you can always call in a professional to help as well.
4. Dispose of the thatch — Now you’re going to want to collect what’s been left behind. Use a standard rake to gather the exposed thatch. You can either throw it away or add it to your compost heap. Avoid the latter if crabgrass and dandelions frequent your yard though.
5. Care for your lawn — Now that the process is complete, your lawn might look a little worse for wear. There’s likely exposed areas of soil dotted around and the grass isn’t looking too happy. Take the time to learn how to overseed your lawn, then feed and water it to give it what it needs to recover. Be sure not to use too much water or fertilizer though; by speeding up the growth, you’re encouraging more thatch to build-up. Check out how much you should water your lawn for guidance.
You might want to learn how to aerate a lawn as well to give it the full treatment once it’s dethatched.
When should you dethatch your lawn?
For general guidance, you’ll want to dethatch your lawn every two or three years. You should aim to do it while your grass is at its peak of growth, and you should only go ahead while it’s healthy as well. Dethatching will take its toll on your grass, so you will want to make sure it’s in its prime of health for the best chance of recovery.
For reference, cool-season grass, such as Kentucky bluegrass, is best dethatched in the early spring or early fall. While warm-season grass, such as Bermuda grass, should be dethatched in late spring or early summer.
You also want the soil to be moist for the best conditions. If it’s too wet, you could pull everything out by the roots, while if it’s too dry the tools will struggle to dig and effectively reach the mulch.
Remember to keep an eye on how thick the layer of mulch is as well — if it’s less than ½ inch, you can put the rake away.
Your lawn should now be free of thatch. This will help your grass grow stronger and healthier in the long run, but remember to keep an eye on it immediately after dethatching. This task does leave it vulnerable and it will need time to recover before it can flourish.
For more lawn tips, tricks, and how-tos, check out our guides on how to plant grass seed, how to make your grass greener, how to stripe your lawn, how to lay sod, 7 common lawn care mistakes you're probably making right now and 7 ways to revive dead grass.