How Do Mulching Blades Work? In-depth Details

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Riding your lawnmower or pushing it in your yard, you may think about how does the mower blade interacts with the grass blade.

To understand the working principle of each blade you fit on your mower, it might look technical to you, but it’s not if you have the proper knowledge.

Before we move onto how do mulching blades work?, let’s get the know-how of certain things which will help you throughout this read.

What Is a Mulching Blade? What do mulching blades do?

Mulching blade is a type of lawnmower blade, once mounted on your mower gives you mulch”

A best and universal mulching blade

Mulching blades can also be referred to as “3-in-1 blade or “all-purpose” blades. As these blades serves three functions which are mulching, bagging and discharging to some extent.

The word “mulch” describes the cuts or pieces you get after mowing your lawn with a mulching mower.

Mulch serves as fertilizer to your topsoil and provides 30% of nitrogen back to the grass; that’s the handy benefit you get with mulching grass clippings.

Below, you can see the mulch I got right after mowing (thanks to the sunlight), which gives me a clear picture 😊.

Mulch Produced After Mulching

Mulching blades are way better than the regular blades. As they cut grass more effieciently into much smaller pieces called grass clippings. Regular blades comes with new mower and also available to buy as mower blade spare parts but never recommended.

regular blades being sold by tractorsupply

Are Mulching Blades Better? Do They Really Work?

As mentioned earlier, mulching blades carry nutritional benefits for your lawn. Mulch adds basic elements that any fertilizer adds to your lawn soil: N :P: K (Nitrogen: Phosphorous: Potassium). It makes your grass look clean and lush green.

Mulch blade working is not only confined to cutting grass, but they also cut leaves and weeds, which is the major problem for large area lawns.

If your lawn is surrounded by the trees that fall leaves every season, then you will see the patches of deteriorating grass due to less availability of sunlight blocked by leaves on them.

Here, the mulching blade really works and cuts those leaves away so your grass can breathe and stay beautiful as always.

Now you can say goodbye to leaf blowers and rakes because the mulching blade will handle this job.

Another benefit is that it works for you so that you don’t have grass piles anymore, which you always worry about where to throw.

Here are the pros and cons of mulching blades that show they are way much better.

  • 3-in-1 blade: cuts leaves, grass, and weeds
  • Increase soil fertility
  • Long-lasting
  • Saves time for mowing
  • No grass clipping piles in lawn
  • Doesn’t work on old traditional mowers

Coming back to our discussion, let’s get further in-depth.

What Does a Mulching Blade Look Like?

There are different parts of mulcher blades that serve different functions.

From the image, you can observe the highlighted parts and get a clear insight.

Mulcher Blades Parts
Part number as in image aboveMulcher Blades Parts
1Curved Body
2 Serrated-teeth edge
3 Flat edge
4 Hole
5 Thickness and length
6 The part that has stamped number

Curved Body

The angle of curvature (curve) of the mulching blade makes its most important part in the play.

It directly controls cutting, lifting, and discharging. The curved angle of this blade creates vacuum conditions or airstream in the deck of your mower, which cuts grass pieces again and again.

Hence producing a finer mulch.

It’s better not to change the cutting angle as it will disturb the mulching operation. Companies give the right built-in curves, so you don’t need to worry about it.

Serrated-teeth edge

Some mulching blades have curved, serrated teeth, usually three if you look from the edge.

The air flows through these teeth, which means increased RPM (rotation per minute) of your mower, more lifting, and more cutting.


Flat edge

Some mulching blades have flat edges like Oregon blades. These blades are thick and produce excellent mulch compared to the serrated-teeth edge blades.

But these blades require more engine power to move as they hinder airflow through them.


The hole is the most crucial part as it decides the correct fitting of a blade.

Look at your shaft first before buying a mulching blade because your blade won’t work if you try to mount an edge with the wrong mounting hole.

Holes come in different designs like circular, five-star, six-star, seven-star to gives a perfect mount.

Some blades come with WASHERS which are used to make the fit right. Some blades come with a reducing washer so you can avoid cracking blade holes or shaft assembly.

Thickness and length

More thickness means less lifting and intense mulching.

Length is concerned with the proper fitting in the deck. Length varies according to the lawnmower deck size.

The part that has stamped number

Blades has a part near the blade whole where you can check the number assigned to a blade that shows its compatibility with more it will mount on.

From the above discussion, now you have a great sense that a landscapist should have to crack the working mechanism of a mulcher blade.

How does a mulching blade works?

How do mulching blades work?

The physics of the mulching blade works like a barber’s machine. When two opposing blades push against each other, they cause shear stress on a localized area, cutting your hair.

Apply this idea to the lawnmower blade rotating at high speed, causing, again and again, shear, which producing final cuttings.

But the mechanism doesn’t end here. The well-known phenomenon behind cutting is the vacuum created by moving blades.

When blades move at high speed in the deck, their curved part creates a vacuum that pulls the grass up and cuts it.

Here is the closed view slow motion video you can observe to understand.

If you observe closely, you will see the suction and cutting mechanism being carried out as the blade moves.

Factors That Control the Working of Mulching Blade

Hight setting of the mower deck matters to create enough suction. So, try to keep it once an inch more than usual.

The shape of the deck: It is another critical factor as it holds the vacuum within it.

Blade length: Larger blades work well and cut well, but they require a more oversized deck to works means a big beast mower will do the job here.

Blades curve: This creates a vacuum.

From the above discussion, here is the quick answer to How does a mulching blade work?

Quick Answer

In short, the mulching blade works by sucking up the grass with the help of the vacuum they create. Vacuum creation is subject to the angle of curvature or curved edges of the blade. Edges functions to suck up air, hold grass tight, and hit it with high inertia to cut.

Photo of author


After doing my master’s in agriculture, I went on with this field for more than 15 years because I love working in green. I have experienced using modern machinery and techniques that can help farmers and landscapers to achieve something great. My goal will be to deliver you the best reviews and information to make the right decision.

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