Benefits of Using a Mulching Lawn Mower

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Person on a riding mower mulching leaves on a large area of grass

As a devoted homeowner, you may wonder, “What are the benefits of mulching mowers? Are they worth the hype?”

Yes, indeed, there are many benefits of using a mulching lawn mower. Recycling small bits of grass clippings back into your lawn has advantages for your lawn, for the environment, and for you.

Why is it called a mulching lawn mower?

You might wonder what lawn mowers have to do with mulch. Good question.

When you first think of mulch, you’ll probably think about the materials you put on your flower beds, bushes, or trees: shredded bark, wood chips, pine straw, etc. But mulch has a broader definition. 

Instead of thinking about the materials, think about what those materials accomplish: They cover the ground or soil. Mulch is any material that covers the soil to provide nutrients, reduce evaporation and erosion, prevent weeds, and control temperature swings.

When you use a mulching mower, the finely shredded grass blade clippings serve as a mulch or covering for your lawn just as the bark is a covering for your flower beds. That’s the idea behind the name mulching mower.

Benefits for your lawn

Let’s start with how mulching mowers benefit your lawn:

✓ Mulching mowers are the machines that best help homeowners “grasscycle” (return clippings to the lawn). The fine bits of grass decompose quickly, releasing nitrogen, phosphorus, potassium, and micronutrients back into the soil. This means fewer fertilizer treatments for your lawn.

✓ Mulching mowers enable on-site recycling. You’re returning grass right back into the ground from which it came. It never even left your lawn.

✓ Mulching mowers will not contribute to thatch buildup (the layer of leaves, stems, and roots between the grass and the soil). Thatch buildup likely means your lawn has too few worms and microorganisms to break down the organic matter. The good news? Finely chopped grass clippings help increase your soil’s microbial activity.

illustration explaining thatch on grass

✓ Mulching mowers chop more than grass. Leave your rake on the pegboard; get out your mulching mower and mulch the leaves instead.

✓ If you prefer to bag or side discharge occasionally, mulching mower blades are still useful. Mulching mower blades are sometimes called 3-in-1 blades because you can use them to mulch, bag, or side discharge if your mower allows.

Benefits for the environment

Why should you care if the grass clippings go to the landfill? 

By retaining your grass clippings on your lawn (or in your compost pile), you keep the grass out of the solid waste stream. It’s like having a recycling facility on your property. If you were to bag the clippings and put them on the curb as green waste, they enter the municipal waste stream and increase the waste management and landfill burden in your city.

infographic showing the materials used in composting. Including the most common brown and green options.

Yes, grass clippings will biodegrade, but turning them back into the lawn or composting them is a better option. Here’s why: In the lawn and compost pile, the clippings receive plenty of oxygen and water to help them decompose into organic matter relatively quickly. 

Landfills, however, are not designed to decompose materials fast like your compost pile. They are primarily designed for disposal and to keep any contaminants out of the environment

Remember the adage, “reduce, reuse, and recycle?” By putting your grass clippings back in your lawn, you reduce the amount of yard waste that goes into the landfill and reuse a “waste” product to grow a healthier lawn. 

Let’s get back to why this is good for your lawn environment: Did you know that “grasscycling” throughout the growing season (when you mulch the clippings back into the lawn), adds the equivalent of one synthetic fertilizer treatment to your lawn each year? That’s right, you can rely on this free mowing by-product to break down and provide valuable nutrients to your lawn or garden beds. 

Benefits for you 

The lawn and environment are important, but what about you? Here’s how a mulching lawn mower provides value for you, the homeowner:

✓ Saves time: No need to bag your clippings or put them on the curb
✓ Saves hassle: No more heavy, clumsy bag attachments to empty
✓ Saves money: One free fertilizer treatment goes into your lawn every year just by mowing the lawn
✓ Helps build a healthy lawn: Mulched clippings help build the soil over time and reduce erosion
✓ Saves on your water bill: Mulched clippings reduce evaporation in your lawn

Mulching mowers are a key component in many homeowners’ lawn care toolkits. They not only cut grass, but also provide a plethora of added benefits that help your lawn, your local environment, and you, the homeowner.

FAQ about mulching mowers

1. What if I don’t have a mulching mower?

Not a problem. Convert your current lawn mower by purchasing a mulching mower conversion kit. Depending on your mower, this may include a new blade or a new blade and a plug for your discharge chute or bag. 

Commercial mowers may benefit from a mulching baffle as well as a mulching blade. Mulching baffles direct airflow under the deck which helps the grass break down into smaller pieces before it lands on the lawn.

2. Will a side-discharge mower provide the same benefits as a mulching mower?

Side-discharge mowers return the grass to the lawn, but the clippings are larger and strewn farther away from the mower. 

The good news? Your side discharge mower may come with a mulching blade. If so, close the side discharge chute and start mowing. If not, buy a mulching kit (and a mulching baffle if needed) to glean the benefits a mulching mower provides.

3. When should I not mulch my lawn clippings?

Disease: If you have a disease or fungus on the lawn, save these areas for last, and attach the bag to collect the clippings.
Weeds: Weeds that have gone to seed do not need to be recycled back into the lawn. This will plant a new generation of unwanted vegetation. Some say you can compost these clippings; most say to avoid it. If your compost pile won’t reach 140 degrees F, it’s best not to compost them.
Leaves: Once the leaves cover more than 50% of the lawn, you may want to bag. (Use the chopped leaf litter as a mulch for your flower beds or as an addition to your compost pile.) Too many leaves chopped up at once can smother the grass. If the leaf coverage is under 50%, go ahead and mulch them in. If you’re still worried about leaving all of that litter, you can bag, mow more frequently, or make two passes over the lawn to chop the leaves even more finely.
Long grass: If you need to cut more than one-third of the blade to bring it down to its ideal height, you have a few options: 1) Only cut one-third of the height, wait a few days, and cut it again. 2) Bag the clippings this time and turn them into the compost pile.
Chemical use: If you’ve used herbicides on the lawn, you can leave them on the lawn as mulch, but don’t use them in your garden or ornamental beds right away. Wait at least two weeks after you’ve treated the lawn. On the third weekly mow, you can start to use them again as mulch or in the compost bin if you wish. (Note: Always follow the recommendations on the label.)

If you’d love to try mulching your grass clippings but don’t have the time to mow, contact one of our local lawn care experts. They’ll be happy to mulch mow and start your lawn on the path to better health.

Main Photo Credit: sk | Flickr | CC BY-ND 2.0

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