What to do When Your Mulching Mower Leaves Clumps of Grass

You have a mulching mower for a reason. You want your yard to look great. You want the benefits of mulching clippings back into the lawn. And you don’t want the hassle of bagging the grass clippings.

The problem is your mulching mower leaves clumps of grass.

First of all, don’t panic! There are a few things you can do to fix the problem.

The solution comes down to technique or equipment. This article will help you troubleshoot the issue and get your lawn looking fantastic.

How a Mulching Mower Works

A mulching mower is a type of lawn mower that mulches the grass clippings instead of discharging them out the back or side of the mower.

Mulching mowers have a blade that is designed to chop the clippings into tiny pieces. The process of mulching the clippings depends on air flow. The blade recirculates the grass and leaves under the deck so the blade can chop the clippings multiple times.

Improper air flow is the major cause of grass clumping up. Next, we’ll look at how to improve airflow. The good news is, most of these fixes don’t cost any money.

Clean Under The Mowing Deck

First, be sure to clean under the mowing deck. This will help to remove any build-up of grass that is attached to the mowing deck. The built up grass can mess up the air flow underneath the deck. Removing the debris under the deck and restore the air flow it was designed for.

Using a Garden Hose Cleanout

Some mowers are equipped with a garden hose connection for cleaning. All that is required is to put the lawn mower on a hard surface, connect the hose, turn on the water and start the mower. The mower will blow the water around under the deck and wash it clean. When the process is complete, turn off the water, disconnect the hose. Then start the mower and let it run for a couple of minutes. This will dry out the mower deck. And you are done.

Scraping Under the Deck

Use caution when cleaning under the deck. Before you do anything, remove the spark plug wire from a gas powered mower or remove the battery from a battery powered mower or unplug an electric mower.

When turning over the lawn mower, make sure the carburetor is on the top side so the crankcase oil won’t drain into it.

Use a plastic scraper or a thin piece of wood to scrap under the mowing deck to prevent scratching the paint. You can also use a garden hose to clean under the deck.

NEVER USE A POWER WASHER under the deck.

If there was a lot of debris under the deck, cleaning it out may have fixed your problem. If it didn’t, try this…

Adjust The Deck Height

If you have a mulching mower, it’s important to make sure that you set the deck height correctly. If you set the deck too low, it will restrict the flow of air and make it difficult for the mower to do its job. The same is true if you set the deck too high. The best way to avoid this problem is to raise the deck height until you see a noticeable difference in the airflow. This will ensure that your mower can mulch your grass properly and with no issues.

The optimal height for a mulching mower is 2 ½ to 3 inches.

Don’t Try To Mulch Wet Grass

If you try to mulch wet grass, the blades will just end up getting clogged and the mower will be less effective. Wet grass is too heavy to be circulated around under the deck. It’s better to wait until the grass is dry before you mow.

Don’t Try To Mulch Grass That Is Too Tall.

Don’t mulch grass that is too tall. If the grass is too tall, it will be more difficult for the blades to cut through it. There is just too much grass for the blade to do its job. All that grass restricts the air flow and you’re more likely to end up with clumps of grass.

Sharpening The Blade

If you want your mulching mower to work efficiently, you need to make sure that the blade is sharp. A dull blade cannot mulch the grass effectively and can actually end up doing more harm than good.

There are a few ways to sharpen your blade. You can use a bench grinder, a file or a drill attachment made specifically for sharpening lawn mower blades.

In any case, you will need to remove the blade from the mower. Once you’ve sharpened the blade, you will need to be sure to balance it. You can do this by simply holding the blade on a screw driver place in the center hole of the blade. If one side is heavier, you will need to grind a little bit off of that side until the blade is level.

If you don’t know how to sharpen the blade yourself, you can take it to a lawn mower shop that can do that kind of work.

Conclusion

If your mulching mower is leaving behind clumps of grass, there are a few things you can do to fix the issue. Be sure to clean under the mowing deck and raise the deck height to improve airflow. If the grass is wet, don’t mulch it – wait until it dries out. Don’t mow grass that is too tall. Lastly, make sure the blade is sharp – a dull blade won’t be able to mulch efficiently.