Mulching Leaves With a Push Mower: Tips
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Mulching leaves with push mower work means running the mower over fallen leaves with the deck set high so the leaves are chopped into small pieces that fall down into the grass instead of being bagged. Extension guidance from Colorado State University says this works best with dry leaves, a high deck setting and a couple of passes, and that the chopped leaves return nutrients to the soil and can help suppress weeds in a dense lawn. The steps below cover the setup, the passes, the limits and the mower features that make the job easier.
Quick answer
- Set the deck to its highest cutting height before you start.
- Mow over the leaves with a couple of passes, so they are chopped into small pieces that can filter into the turf.
- Use dry leaves. The guidance says mulching works better with dry leaves than wet ones.
- Stop when you can still see grass through the mulch. If you cannot, the layer is too thick and you should mow again after removing some leaves or making a second pass.
Why mulching leaves works
Leaves are mostly carbon and contain nutrients that the grass and soil can use. When a mower chops them finely, the pieces settle into the turf, where soil organisms break them down. Colorado State University notes that mulched leaves return nutrients to the soil, feed earthworms and add moisture for turf roots. That makes the practice a useful alternative to raking, bagging and hauling leaves to a curb or dump.
The same guidance says that a dense turf is a strong defense against weeds. Mulched leaves can cover bare spots where weed seeds would otherwise sprout. Michigan State University experts, quoted in the same extension guidance, report a near elimination of dandelions and crabgrass after three years of this practice. The benefit depends on keeping the lawn thick, so mulching works best as part of regular lawn care rather than as a one-time fix.
Setting up the mower
Start with the deck height. The guidance says to set the mower to its highest setting, so the blade does not push the leaves flat or scalp the grass. Most push mowers have a height lever with several positions. The listings in our product data give different ranges, so check the owner’s manual for the exact position on your model. For example, the SENIX LSPG-M7 listing gives a range from 1.25 to 3.75 inches with six positions, and a mulch plug is included with that model.
Next, prepare the mower. Remove the grass bag, because a bagger collects the clippings rather than mulching them. If your mower has a mulch plug, fit it as the owner’s manual describes for mulching.
Making the passes
Make a couple of passes over the leaves. The guidance says the aim is to chop the leaves into small pieces, and one pass often leaves large clumps. On the first pass, mow in a line across the leaf-covered area. On the second pass, cross the first pass at an angle or go over the same rows again, so the mulch becomes finer and spreads more evenly over the lawn.
Spread the leaves as you go. A thick pile will not chop well and can smother the grass underneath. The guidance says to avoid leaving leaf litter sitting on the lawn, because it can smother grass and promote mold and disease. If you can see clumps after two passes, rake a little of the material away from the thickest spots and mow again. A thin, even layer that you can still see grass through is the target.
When to mulch and when not to
The guidance says mulching works better with dry leaves than wet ones, so wait for a dry day if you can. It also points to a thin layer as the target, so mulching in several sessions as the leaves fall is a practical way to keep each layer thin.
Mulching is not the right choice for every use. The Colorado State guidance notes that whole leaves are preferable to mower-chopped leaves for compost, because finely chopped leaves compress more easily and can limit airflow. If you want a compost pile, collect the leaves whole. Mower-chopped leaves can still go into garden beds, and the guidance suggests chopping them with a lawn mower before adding a layer of six to eight inches to vegetable beds.
Lawn benefits and limits
The guidance says mulched leaves return nutrients to the soil and add moisture for turf roots. It also says Purdue research found that mulching leaves into the lawn did not increase thatch or disease and did not change soil pH. That is a useful point for anyone who worries that leaves will cause problems in the lawn. The same guidance does not say that mulching replaces fertilizer or aeration, so keep up with the other parts of lawn care.
The benefits assume a healthy lawn. If the turf is thin or bare in places, leaves can cover the grass for too long and make the problem worse. Mulch lightly over thin areas, and rake off any leaves that stay on the grass for several days.
Mowers that handle mulching
Many push mowers in our product data include a mulching feature alongside bagging and side discharge. Two examples are the CRAFTSMAN Electric Push Lawn Mower, a corded 20-inch model with a 3-in-1 setup for bagging, mulching and discharge, and the SENIX LSPG-M7, a 21-inch gas model with a 140 cc engine and a 3-in-1 steel deck for mulching, side discharge and rear bagging. The PowerSmart 21-inch gas mower in our data is listed with a mulching and side-discharge deck and six cutting heights. The BILT HARD 21-inch gas mower lists 3-in-1 operation with eight cutting positions in one listing and ten in another. Check that the mower you choose lists a mulching feature, and use its highest deck setting for leaf work.
A mulching feature mainly changes how the cut material is handled under the deck, and the chopping still depends on the blade. The extension guidance does not cover blade sharpening or deck cleaning, so follow your mower’s manual for those tasks.
Common mistakes
- Mowing with the deck set low. A low setting can push the leaves flat and scalp the grass.
- Mowing one time over a thick pile. Two passes, with raking of thick spots, give better results.
- Mulching wet leaves. The guidance says dry leaves work better.
- Leaving leaf litter on the lawn for days. The guidance warns it can smother grass and promote mold.
- Using mower-chopped leaves for a compost pile. The guidance prefers whole leaves for compost.
FAQ
Do I need to remove the bagger to mulch leaves?
Yes, for a mower that has a separate bagger, remove or leave off the bag so the clippings and leaves stay in the deck and are chopped. Check the owner’s manual for the mulch plug or mulching kit your model needs.
What deck height should I use?
Use the highest setting on the height lever. The guidance says to set the mower to its highest setting for leaf mulching, so the blade does not press the leaves flat or cut the grass too short.
How many passes do I need?
The guidance says a couple of passes is usually enough. Make the second pass at an angle to the first, and check whether the leaves are in small pieces. If large clumps remain, rake some away and mow again.
How do I know the layer is not too thick?
If you can still see grass after mulching, the layer is not too thick, according to the guidance. If the grass is hidden, rake off some of the material and mow again.
Can mulched leaves help with weeds?
Michigan State University experts, quoted in the Colorado State guidance, report a near elimination of dandelions and crabgrass after three years of mulching leaves into the lawn. The effect depends on keeping the turf dense, so the result will vary by lawn.
Are mulched leaves good for compost?
The guidance says whole leaves are preferable for compost. Mower-chopped leaves can compact and limit airflow in a pile, so keep whole leaves for the compost bin and use mulched leaves on the lawn or in beds.
Bottom line
Mulch leaves with a push mower when they are dry, the deck is at its highest setting, and you can make two passes that leave a thin, even layer you can see grass through. Keep whole leaves for compost and clear thick piles from the lawn. For the mower types that handle this job, see How to Mulch Leaves With a Lawn Mower and Best LawnHog Electric 19-Inch Mulching Mowers.
