This: Burning Leaves
Pros: It's a quick and easy way to get rid of lawn waste, and many people seem to relish the smell. Plus, what's not to like about fire?
Cons: Answer: Your house burning down. In addition to being a fire hazard, burning leaves introduces a lot of pollutants into your backyard air, such as particulate matter, carbon monoxide, and hydrocarbons—a class of chemicals that can be toxic, irritating to your respiratory passages, and carcinogenic, according to the U.S. Environmental Protection Agency (EPA). The EPA also notes that because leaves are usually moist, they burn poorly and emit even higher levels of those dangerous hydrocarbons. And, for all these reasons, burning leaves could be illegal in your neighborhood.
That: Mulching Leaves
Pros: Chopped-up leaves are a great fertilizer for lawns, particularly since fall is the best time of year to fertilize. The decaying organic matter feeds all the beneficial microorganisms in the soil, which also helps the soil retain more moisture, and they continue to feed the soil even after your lawn goes dormant in winter. Come spring, you'll have healthier grass. Plus, no more painful raking; all you need to do is run over the leaves with your lawnmower.
Cons: If you're mulching your leaves with a gas-powered mower, you're pumping pollutants of a different sort into the air. According to a 2003 report from the EPA, mowers contribute as much as 5 percent of all ozone-forming emissions and produce as much pollution as driving a car 20 miles.
This or That?
Go with…That. Mulching leaves. And make it super-green by opting for a human-powered reel mower rather than one that runs on gasoline. If you're burning leaves, you're allowing a free, valuable fertilizer to simply go up in smoke. And that smoke and all the particles it brings with it are settling deep into your lungs, possibly causing you health problems down the line. The pollution becomes even worse if you pile them up using a leaf blower, which can belch out sulfur dioxide and other smog-producing pollutants at a hearing-loss-inducing level of 105 decibels.
Mulching leaves is fairly self-explanatory, but here are a few extra tips to get the most out of your mulch:
• Remove your grass catcher. You don't need to collect the mulched-up leaves and then sprinkle them back onto your lawn in order to fertilize evenly. Just take the grass catcher off the back of your mower and let them land where they will.
• Mulch them to dime-size bits. The fertilizer company Scotts recommends mulching your leaves into pieces about the size of a dime and mowing over them until you can see about half an inch of grass peeking through your layer of leaf clippings.
• Mow high, then repeat. The Michigan State University Cooperative Extension service has found that you'll get the best results if you set your mower at the same height as you would to mow your grass. Also, sharpen your mower blades and, if it's possible, mow the leaves when they're dry. Mow regularly, as well, taking care not to leave whole leaves on your lawn for more than three or four days. Doing so prevents the leaves from killing your grass entirely.
• Consider composting. If you just don't like the look of leaf fragments on your grass, shredded fall leaves make a great addition to a compost pile. If you have an electric leaf blower, another way to shred them is to set the blower on reverse and suck 'em up. Then dump the bagful of shredded leaves onto the pile; by spring they'll have decomposed into a rich soil amendment for your garden. See our topic page on composting for more compost pile tips.