Mulching mowers work by cutting the grass and swirling the clippings multiple times within the deck. These finely chopped clippings then drop onto the lawn to nourish the grass and soil.
In this article, we’ll delve into the details of how mulching mowers work, the mechanics behind them, and provide some useful tips on how to use them efficiently.
What is a Mulching Mower?
Mulching mowers are a type of mower that cuts the grass and shreds the clippings into very small fragments that are then released onto the grass and soil. These finely cut grass clippings then decompose quickly and return organic matter into your soil, acting as a mulch and fertilizer for your lawn.
Mulching lawn mowers are a great investment for those who are into grasscycling, whether for environmental reasons, to save money, or simply to reduce time and effort.
If you’d love the benefits of having grass clippings returned to your lawn but don’t have the time to mow, hire a local lawn care pro to mulch-mow your lawn this growing season.
See Related:
- Reasons to Use Grass Clippings as Mulch
- Mulching vs. Bagging Grass Clippings
- Mulching vs. Side Discharge: The Best Way to Deal with Grass Clippings
How a Mulching Mower Works
Mulching mowers use a specially designed deck and blade(s) to mulch the grass in three steps:
1. Cut the grass: First, the mower cuts the grass blades at the height you’ve chosen.
2. Recirculate the grass: Then, because of the angled edges of the blade(s) and the specially designed deck, the grass clippings swirl multiple times within the deck and are cut repeatedly into tiny pieces.
3. Deposit mulched clippings: Then, as you push (or ride) the mower, it deposits the mulched clippings over the lawn, forming an evenly distributed mulch layer.
Pro Tip: If you’re considering purchasing a mulching mower, check out our list of the Best Mulching Lawn Mowers.
The Science Behind Mulching Mowers
How (and why) is a mulching mower able to shred the grass clippings the way it does? In short, due to its blade and deck. These are the mechanics behind mulching mowers:
1. Blade design: Mulching blades are specially designed to shred your grass clippings multiple times. They are different from regular blades — mulching blades usually have three cutting edges, more than a regular mower blade. But these blades also help direct airflow, pushing the cut grass up into the deck instead of back to the grass catcher bag.
2. Cutting chamber aerodynamics: A closed and specially engineered deck design, along with the shape of the blade, creates a circular airflow that causes the grass clippings to swirl up and down within the deck.
3. Making multiple cuts: With this swirling motion and the three cutting edges, the grass clippings are cut multiple times before being released into the lawn.
Mulching Mower vs. Regular Mower
But how is a mulching mower different from a regular mower? Well, the purpose of a mulching mower is to mow your lawn while shredding the grass clippings, while the purpose of a regular mower is simply to cut the grass at the desired height.
The table below shows in detail the differences between mulching mowers and regular mowers:
| Mulching mower | Regular mower |
| Turns grass clippings into small, finely chopped pieces | Leaves grass clippings at the size they were originally cut |
| Has a closed deck that distributes grass clippings evenly as you mow | Releases grass through a discharge chute into the lawn or into a grass catcher bag |
| No need to spread the clippings after mowing | You must bag the clippings or rake them to evenly distribute them over the lawn |
Why is a mulching mower the best option for grasscycling? While you can spread the grass clippings produced by a regular mower over your lawn, because they are longer, they can entangle and form irregular patches that “suffocate” your lawn.
These patches of entangled grass will prevent your turf from getting sun and water, causing your grass to grow in clumps. In the worst-case scenario, they can also lead to common lawn diseases.
Pro Tip: Mulch mowing also works for the fall leaves in your yard. Just ride your mulch lawn mower over them, and ta-da! Now, instead of spending time and energy raking and collecting those leaves, they are ready to nourish your lawn and soil over the upcoming winter.
Here’s a short video comparison of how regular mowers and mulching mowers differ:
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Tips for Using a Mulching Mower
Using a mulching mower is even easier than a regular lawn mower since you’ll skip the part where you collect or spread the clippings. But here are a few lawn mowing tips to optimize the time you invest in mulch-mowing your lawn:
- Follow the one-third rule. Aim to mow at least once per week during the growing season, never cutting more than one-third of the grass blade. Cutting more than one-third of the leaves’ surface can overstress your turf, making it more susceptible to dehydration and disease.
Also, mowing more than one-third of the grass blade creates long grass clippings that a mulching mower won’t be able to break down as efficiently. - Mow when the grass is dry. Mowing damp grass is not a good idea, and this rule also applies to mulching mowers. Besides preventing grass from clumping, mowing when the grass is dry also ensures the grass clippings are cut efficiently.
- Don’t mulch diseased or weedy grass. If your lawn is diseased or has a weed problem, mulching the grass clippings can make it worse. To avoid spreading fungi and weed seeds over the lawn, bag and dispose of the grass clippings instead.
- Keep the mower clean: Whether you use a deck wash port or raise/tip the mower to clean it, keeping a clean mower deck is critical for proper airflow and mulching performance.
See Related:
- How to Mow a Lawn the Right Way
- Best Way to Clean a Lawn Mower Deck
- DIY Lawn Mower Maintenance Guide
- How to Winterize Your Lawn Mower
FAQ About Mulching Mowers
Yes, most lawn mowers can be converted to mulching mowers by upgrading them with a mulching plug (to close off the bagging chute) or a mulching kit. Mulching kits are sold at your local hardware or home improvement store and online and come with the mulching plug and mulching blades.
No, you don’t need special blades for mulching (a mulching plug usually does the job if you’re not willing to buy the kit), but specialized mulching blades are guaranteed to break down your leaves or grass clippings into mulch much more efficiently.
Using your grass clippings as mulch can help you save around 25% on fertilizer costs annually. Although it’s an expensive purchase upfront, a mulching mower can help you cut down on your need for synthetic fertilizer in the long run.
When to Call a Professional
If mulch-mowing your lawn sounds like a good idea but you’d rather have someone else tackle this weekly chore, why not hand it over to a LawnStarter pro? Get in touch with a lawn mowing pro near you to recycle your grass clippings for a healthier, more sustainable lawn.
Source:
City of Maywood, California: Grasscycling
Main Image Credit: lara-sh / Adobe Stock
