One of the best ways to clear your lawn of autumn leaves is to mulch them into small particles that break down and return to the soil next spring. The tool to do that mulching is your mower. If you have six inches of leaf cover or less, this may be easier than using a cordless leaf blower to get them off the lawn or or by using a rake to gather them onto a tarp and drag somewhere for disposal.

If you have more than six inches of leaf cover, the method will still work, but you’ll have to remove several inches of leaves with a blower or a rake (or both) before you begin the mulching process.

Mowers that are equipped to side discharge, mulch, and bag are particularly adept at leaf mulching because their ability to do all three processes helps you to work through a wide variety of mowing conditions, leaf moisture, lawn moisture, and debris such as pine needles and nuts that may be mixed in with the leaves.

There are a few things you need to keep in mind about autumn leaf mulching

First, the lawn isn’t going to look as pristine as it does when you remove every single leaf from the vicinity. We’re not going to tell you that the two methods are equivalent. Second, we’re not going to tell you that there’s nothing to it. Mulching leaves with a mower is hard work. Whether it’s a better solution for you than removing the leaves will depend on how you like to work, and how thick or damp the leaves are, and what your goals are for the appearance of the yard when you’re done. Many people opt for a combination of the two methods, shooting for pristine leaf removal on the front of the house and using some combination of mulching and removal elsewhere on the property.

Prepare to Mulch

Mulching leaves is not all that different than standard lawn mowing. Assuming you have a three-function mower, set the mower up to its full height setting.

leaf mulching
Colin Aylesworth
Every multi-purpose mower has some means to control clippings and whether they are kept recirculating under the deck (mulching), discharged out the side or into a bag. If your mower has a mulching plug, install it by sliding it into the rear discharge port. Some mower designs omit the plug and have a pivoting plate that closes off the deck. If so, close the mower deck by moving the lever that controls this to the mulching position.

Double check that you have the mulch plug installed.

leaf mulching
Colin Aylesworth
Whether the mower uses a single deck height adjustment, two levers or four, set the mower to its full deck height and take a test run.

Insert the side discharge chute

leaf mulching
Colin Aylesworth
Install the side discharge chute on a 3-function mower (mulches, side discharges or bags). Some mowers have a discharge chute that fits in the rear of the mower. Be sure that it’s securely fastened. The most common design is shown here. Lift the spring-loaded deck hatch and insert the chute’s pins under the cover’s hinge pin. Give a firm tug on the chute to be sure that it’s securely fastened.

Take a test run with the mower by cutting a stripe. You should see that the leaves are thoroughly shredded. If not, lower the mower deck by a couple of notches and make another test pass. Once you have the mower setting where you need it, cut in stripes, discharging the shredded leaves so that the next pass (in the opposite direction) recuts the debris discharged in the first pass. If you want more thoroughly-mulched leaves, remove the side discharge chute, insert the mulch plug and recut the area, mowing at 90-degrees to the axis of the first cut.

Now, suppose your mower doesn’t have a side discharge port, it’s a two-function mower (mulches and bags); it will still mulch leaves. Raise the deck all the way up, and make a test pass. The slower you go, the more mulching action you’ll get. See what your results look like and adjust the mower deck to get a thorough mulching action. If the leaves aren’t thoroughly mulched, make a second pass over the area, mowing in rows that are 90 degrees to the first rows.

Wet Leaves and Other Problems

The general leaf mulching advice we give above refers to dry leaves and work conditions in which there is no more than a light breeze. Things can go sideways when the leaves are damp; if there is plentiful debris mixed with the leaves, such as pine needles, acorns, sweet gum seed pods, locust seed pods, acorns, and twigs; or if the wind is either steady and unfavorable or shifts around a lot. In that case, you have to get creative.

First, if you find that your machine isn’t an effective mulcher, consider switching to a more aggressive blade. Notched blades specifically designed for mulching grass may also improve the mower’s leaf mulching performance.

There are two other mowing patterns to consider. You can side discharge and mow a counter clockwise rectangle or square (mulched leaves are discharged and not recut) or clockwise (mulched leaves are discharged and recut on the next pass). If the mulched material is thick, you can make an additional pass over the area and bag some or all of the debris. Or you can make a final pass over the area, mowing in rows. In that case, remove the discharge chute, insert the mulch plug, and make a second pass in rows over the mulched area.

If you decide to bag some of the mulched leaf mixture, you’ll find that it’s an excellent addition to your compost pile. The combination of grass clippings (nitrogen) and the mulched leaves (carbon) breaks down quickly. Anybody who has ever bagged leaves will tell you that the typical grass bag will fill up in seconds. Consider one of these super-size bags for the job, which could be a real problem solver.

Finishing Up

With the lawn cut and the leaves mulched, it’s time apply a winter-blend fertilizer. These are products with a chemical analysis approximately of 26-2-12, 24-3-12, or 20-0-10. Those three numbers are known as the fertilizer’s NPK (the letters from the Periodic Table of elements) that signify the amount of nitrogen, phosphorous and potassium in the fertilizer, in that order. The last number, for potassium, should be as high as possible. It helps to build the grass’s cold hardiness and improves its ability to store carbohydrates. With increased soil temperature and sunlight, the grass will come roaring back next spring.

Finally, don’t neglect the mower. Get it ready for next spring by giving it a thorough year-end overhaul. Here’s full a report on how to tune up a tired gas engine mower. Most importantly, tank the mower up with ethanol-free gasoline or fresh fuel with stabilizer added. This will prevent the slow chemical degradation of the fuel in the mower over the winter. If you’re working with a cordless mower, bring the batteries and the charger indoors, to a warm place, and follow the manufacturer’s instructions in the owner’s manual for battery storage—in many cases, this will be to leave the batteries on the charger over the winter months. With the mower ready to go and the yard fertilized, you’ll have a jump on next spring.

Headshot of Roy Berendsohn
Roy Berendsohn
Senior Home Editor

Roy Berendsohn has worked for more than 25 years at Popular Mechanics, where he has written on carpentry, masonry, painting, plumbing, electrical, woodworking, blacksmithing, welding, lawn care, chainsaw use, and outdoor power equipment. When he’s not working on his own house, he volunteers with Sovereign Grace Church doing home repair for families in rural, suburban and urban locations throughout central and southern New Jersey.