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Dethatching versus Scarifying - What's the Difference?

Spring is here, and if you're looking to make your lawn the best on the block, it needs to be taken care of. Along with regularly watering, fertilizing, and aerating your lawn, dethatching (and/or scarifying) is one of the core parts of lawn maintenance. Regularly doing so will help your lawn stay green and lush for years to come. In this article, we'll discuss the differences between each procedure, as well as present some best practices to get the most out of your yardwork. And no matter what your yard needs, WEN has a dethatcher / scarifier for you.

The Short Answer

In short: dethatching removes up the thatch layer that builds up between the soil and the lower parts of the grass blades. Scarifying reaches down deep, cutting grooves into the soil to remove moss and other buildup, as well as provide some aeration to the soil, and is a more intense process than dethatching.

The Long Answer

Good, you're still reading! Let's dive a little deeper. 

The Basics

Like all plants, grass needs four basic ingredients to thrive: light, water, food, and air. If any of these ingredients are missing, you'll end up with a subpar lawn and a letter from your obnoxious HOA president, Kevin. 

Thatch is the layer of dead grass, clippings, leaf pieces, pine needles, and other light debris that accumulates between the soil and the lower parts of the grass blades. Some thatch is good for your lawn; the layer insulates the soil in very cold or very hot weather, helps prevent excess moisture evaporation during drought, and provides a slight cushion as you walk on the grass. However, too much thatch can stifle growth by preventing air and water from reaching the soil. A good rule of thumb is to try to maintain roughly 1/2 inch to 3/4 inch of thatch. If there's a lot more than that, or if it's difficult to push your finger through the thatch layer to the soil, it's probably time to dethatch your lawn. 

Thatch isn't the only potential culprit if you're seeing weaker-than-expected grass growth. If your soil is compacted, or if the grass is competing with moss or damaged by a fungus, scarifying may be the better option. A scarifier works a bit like a miniature tiller - its blades reach down deep to remove moss, fungus, thatch, and other unwanted buildup from your lawn. At the same time, it scarifies (cuts grooves into) the ground, resulting in better drainage aeration for your lawn and, overall, better growth.

Scarifying (left) is more intense than dethatching (right).

When to Dethatch

When to dethatch varies; if your lawn is prone to thatch buildup (especially if you use a mulch setting on your lawn mower, or have certain species of grass), you'll need to dethatch more often. Choose a time when the grass is actively growing, and the soil has some moisture. In the northern half of the US (where cool-season grasses dominate), this will usually be in the early spring or early fall. For the southern half of the US (where warm-season grasses dominate), this will usually be in late spring through early summer.

Make sure to keep the following tips in mind:

  1. Before dethatching, make sure you have not fertilized in at least a few weeks. You should fertilize after dethatching.
  2. Make sure the soil is moist, but not soaking wet. Don't work on a wet lawn.
  3. Mow your grass to around half its normal height.
  4. Clear your lawn of any sticks, stones, wires, ornamental flamingos, or other obstructions.
  5. Mark any utility lines or sprinkler heads, and avoid them.
  6. Follow the instructions in your dethatcher's owner's manual.
  7. When dethatching your lawn, use a back-and-forth S-pattern, with slightly overlapping rows. 
  8. When you're done, remove any thatch left on the lawn. Fertilize and water your lawn.

Dethatcher head from the WEN DT1516 16-inch 2-in-1 dethatcher and scarifier.

When to Scarify

Scarifying is a more intense process than dethatching, and carries some risk of pulling up grass roots along with moss, fungus, thatch, and other unwanted debris. Generally, it's used more for lawns that need heavy-duty renovation. Consult your local professional landscaper, or local university's agricultural extension office, if you're not sure whether dethatching or scarifying is more appropriate for your lawn. 

If you choose to scarify, increase the depth setting in spring (April - May). The lawn is actively growing and will recover much better during this season. If the summer is wet, consider scarifying again in late summer or early fall, using a decreased depth setting. Do not scarify during periods of hot, dry weather. If the summer is very hot or dry, do not scarify again in fall. This will stress your grass and possibly kill the lawn.

The same tips apply for scarifying as for dethatching.

The scarifying head from the WEN 20716 20V Max cordless brushless 2-in-1 dethatcher and scarifier.

Some Notes About Aeration

Core aeration (also known as coring or aerifying) is a different procedure entirely; a core aerator removes cylindrical plugs of grass, thatch, and soil from your lawn. This allows air, water, and nutrients to enter the soil, as well as helps mitigate compaction. Generally, aerate every year if you have a lot of traffic on your yard, or if it's prone to compaction (especially if your soil is high in clay content). If your soil is more sandy or loamy, you may be able to aerate every 2 or 3 years. Scarifying your lawn is not a substitute for aeration; they're two completely different processes.


Thanks for reading! If, after reading this article, you have any questions about dethatching and scarifying, or about which WEN dethatcher / scarifier is right for you, please feel free to give us a call at 1-847-429-9263 (M – F, 8 – 5 CST), or drop us a message here to talk to our friendly and knowledgeable technical support team.

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