What Is A Mulching Lawn Mower? (The Secret to Perfect Lawns?)

what is a mulching lawn mower

No doubt you’ve heard a lot of talk about mulching lawn mowers, but what exactly is a mulching mower, how does it work, and is it better than a regular mower?

I love a lush, green lawn. Who doesn’t?  And I’ve used a mulching lawnmower for years and believe it can be great for your lawn!

In this article I’ll explain everything you need to know…

What Is A Mulching Lawnmower?

A mulching lawnmower is designed to cut grass and then chop the loose blades of grass multiple times with a specialized blade and mowing deck. This turns the cuttings into a fine mulch, which is evenly spread over the grass. The finely chopped mulch shades and fertilizes the lawn as it goes.

A mulching lawnmower does the exact same job as a regular lawnmower. Still, with one exception: it also chops the cut grass into small pieces and lays it back on the grass to sink in as fertilizer. 

If you love the smell of fresh-cut grass like I do, you’re in for a treat with a mulching mower. Because it cuts the same blade of grass multiple times to mulch it, there is a wonderful earthy, cut grass smell when you use one.

I also prefer a mulching mower to a regular one because I don’t need to use the bag attachment, which needs to be regularly emptied. I don’t have to rake up cut grass that gets pumped out the sides. It’s easierbetter for my lawn, and more eco-friendly!

How Does A Mulching Mower Work?

how a mulching mower works

A mulching lawnmower finely cuts grass and returns the clippings as mulch to the lawn. Blades create a vacuum that keeps clippings suspended for multiple cuts. The smaller clippings promote decomposition, and the mulch enhances the soil.

I’ve used every kind of lawnmower there is: push mowers, sit-on mowers, you name it. But one thing is always the same: you can’t see what’s happening under the mowing deck. 

The good news is that understanding how a mulching lawnmower works is easy:

  1. The mulching mower blades lift and cut the grass,
  2. The airflow in the mower deck blows the cuttings around, allowing them to be cut and mulched into small pieces,
  3. The small bits of grass fall back onto the lawn to decompose and act as fertilizer.

Is Using A Mulching Mower The Same As Grasscycling?

When I use a mulching mower, I like to think of it as simplified composting. Instead of lugging the grass clippings from the mower to the compost heap and back again once the compost is ready, I leave it at the source and let nature do its thing.

The principle behind grasscycling involves leaving the cut grass on the lawn to decompose and leave all the good nutrients at the source. So, by using a mulching lawnmower, you are effectively grasscycling.

A few advantages to mulching lawnmowers:

In all the years that I’ve been using this kind of mower, I’ve seen my lawn improve in these ways:

  • My grass is thicker and looks healthier,
  • I have fewer weeds growing in the lawn because the clippings help suppress weeds rising,
  • My lawn drainage is better because the fertilized soil just underneath the grass can hold more water

Not only have I seen these benefits for my lawn, but whenever I tell my friends and family about it, I tell them about these three things, too:

  • It’s a great time saver – Not having to stop and empty the bag whenever it gets full knocks off a lot of mowing time,
  • I’m helping with the environment – By not bagging my lawn clippings and sending them off to a landfill,
  • It’s the cheapest way for me to fertilize my lawn – because the grass is already mine and ready to be used; I don’t have to buy fertilizer and have it spread,
  • It’s the simplest way for me to fertilize my lawn – because it happens while I cut the grass!

Before using a mulching mower, I spent time and money on lawn fertilizers. Not only were some of them expensive, but it took hours to apply them evenly across the lawn. If you ask me, using a mulching lawnmower is not only the smart move but the most economical one as well. 

Does A Mulching Mower Use A Specialized Blade?

a mulching mower uses a special blade

If you turn a mulching mower over, you’ll see the blade looks a little different from a regular mower’s. The blade is curved to create an upward suction and most mulching blades I have seen have a serrated edge or an edge that looks like it’s from a horror movie with sharp, raised teeth.

These serrated edges or teeth help the blade ‘mulch’ the cuttings, chopping up many pieces of grass each time the blade turns. The grass that lands back on the lawn has been chopped into bits about the size of a grain of rice.

It’s pretty cool!

How Is A Mulching Mower’s Deck Different To A Regular Mower?

Take a closer look at the deck of a mulching lawnmower. Compared to a regular mower, a mulching mower usually has a closed deck. This deck creates a vacuum that pulls the grass clippings into the air, allowing them to be mulched by the blades.

Most mulching mower decks also have baffles to help spread the clippings evenly on the lawn as the mower moves.

When To Use A Mulching Mower?

Sometimes, I let my lawn grow too long. It’s not something I like to do, but sometimes it happens, and when it does, I know that’s not the best time to use a mulching lawnmower. 

I recommend using a mulching mower when the grass is relatively short. Anything longer than about 4 inches and the mower will struggle. I once tried to cut 7-inch grass with a mulching mower, and within the first few yards, the mower was getting clogged. I also saw that the grass landing back on the lawn was uneven and left a thick layer on top of the lawn. 

In the end, I had to rake it all up again anyway!

I figured out that the blades couldn’t handle the amount of grass being lifted and cut, dropping most of it to the ground before it could be mulched.

If you use a mulching mower at the proper length, the finished appearance should look as if the clippings were collected 🙂

Is A Mulching Mower Better Than A Regular Mower?

Mulching mowers aren’t better than regular mowers. They each have their own use and function. A standard mower will be the better machine if I have long grass that I need to cut. But, over the long term, when I mow my lawn regularly, and the grass doesn’t grow longer than about 4 inches, then a mulching lawnmower has far more benefits than a regular mower.

I’ve also discovered that my mulching lawnmower helps my lawn to stop thatch buildup. Thatch isn’t good for your lawn; it happens when successive layers of grass die and build up between the soil and the growing layer of grass on top. This is a problem because it prevents nutrients and water from reaching the roots.

Mulching mowers help to slow down thatching. I’ve seen a lawn improve in a matter of weeks because the decomposing mulch breaks down the layer of thatch.

Mulching Mower Vs. Regular Mower

The chief difference between a mulching mower and a standard mower is what it does with the cut grass. Regular mowers cut the grass and then push it out the sides, but a mulching mower chops the grass into small pieces and leaves it on the lawn to decompose and fertilize.

Mulching MowersRegular Mowers
Cut the grass and then mulch it by chopping each blade into small pieces.Cut grass only.
Does away with the need to rake excess grass or empty the collection bag.Collection bags need to be emptied regularly.
Mulching mower blades are curved and often have teeth or serrated edge.Regular mowers have straight blades. 
Have a sealed and rounded deck to create a vacuum to pull the grass upwards.Have a dome-shaped open deck.

What Is The Best Mulching Lawn Mower?

While this is usually a question of preference, I think the three best mulching lawnmowers on the market at the moment are these: 

Mower NameMower Type
Greenworks 25022 Corded Lawn MowerCorded lawnmower
EGO LM2150SP Cordless Lawn MowerCordless battery powered lawnmower
YARDMAX 21 in. 170cc 2-in-1Gas push lawnmower
Husqvarna YTH18542Ride on lawnmower

(Amazon links)


Here are a few other common questions that people ask me:

Why Is My Mulching Mower Leaving Clumps?

Your mulching lawnmower will leave clumps if the blades are blunt or the grass is too long (longer than +-4 inches) and cannot be mulched correctly before landing back on the lawn.

Why Is My Lawn Mower Not Mulching?

The main reason a mulching lawnmower will not mulch grass is because the blades are blunt.

How To Sharpen Mulching Lawn Mower Blades

Sharpen your mulching lawn mower blades with these three steps:

  1. Use a wrench to loosen the nut on the mower’s blades and remove them altogether.
  2. Use a power sharpener, angle grinder, or file to sharpen the blade’s edge. Consult the manufacturer’s recommendations in the owner’s manual for further information on blade sharpening.
  3. Bolt the blade back in place.

If the blades are cracked, chipped, or damaged, they must be replaced.

Which Way Do Mulching Blades Go On A Mower?

The blades on a mulching mower should rotate counter-clockwise. To check the rotation direction of the blades, check for an arrow on the edge or inside the blade cavity. The indicator will point in the correct direction of the blade’s rotation. 

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