Grass Clipping Disposal: Does Leaving Grass Clippings on the Lawn Cause Thatch?

How To Dispose of Grass Clippings – the Options

How can you dispose of grass clippings? There are several options, depending on where your live.

In many places in the U.S., you can still toss your grass clippings in your regular trash bin, to be hauled off the the landfill. For many reasons, this is a really bad option. The landfills are already overflowing, necessitating digging new ones ever further away from the cities they serve, and requiring even more air polluting trash hauling miles. In addition, grass clippings, like all plant waste, decay in landfills, and produce methane in the process, significantly contributing even more to the air pollution problem, and speeding up climate change.

If curbside composting is offered in your area, that’s a much better way to dispose of your grass clippings. They don’t end up taking up space in the landfill, we don’t overburden the landfills, the clippings don’t generate greenhouse gases as they decay, and the compost is actually used by farmers in place of chemical fertilizers. An added benefit is the reduction in chemical fertilizer runoff, and the substantial water pollution problems that creates. However, curbside composting of grass clippings does require that trucks haul the lawn waste to composting facilities. Still, this is a vast improvement over disposing of grass clippings in the trash.

The best option – environmentally and for us personally – is to just “dispose of” the grass clippings by simply mulching as we mow, and letting them decompose naturally, in place. They’re not being hauled anywhere, and the practice provides many side benefits, described below.

But what about the problem of thatch, and the health of our lawns?

The Lawn Ranger: What Happens When You Leave Grass Clippings on the Lawn

It’s time for a showdown…between law-abiding homeowners and the grass clippings running rampant on their lawns. Could these outlaws be contributing to the dastardly thatch threatening to destroy their turf? Find out in this action-packed installment of EcoMyths.

First, let’s tip our hats to today’s info-wielding heroes: Professor Peter Landschoot, PhD, who directs Penn State’s Center for Turfgrass Science, and Aaron Patton, PhD, a professor of agronomy at Purdue University and Purdue Turf Tips blogger. Short story is, both are shooting straight from the hip when they urge us to let grass clippings lie.

Lifting the Mask on Thatch – the Remains of Grass Clippings

For those lawn-owning folks lucky enough to have never heard of thatch, here’s a quick primer. In addition to being a cheeky nickname for a certain former British prime minister, thatch is an intermingled layer between the turf surface and the soil beneath that’s made up of stems, root material, and other slow-to-decompose plant parts. It can affect turfgrass virtually anywhere.

A little thatch can actually be good, say Landschoot and Patton, because it acts like mulch, holding water and microbes in the soil and providing cushion for turf. In fact, Kentucky bluegrass, which is more prone to thatch than some other grass species, is often used on football fields thanks to its injury-reducing sponginess.

But a host of problems can creep up when thatch takes over. More than an inch of thatch will restrict the movement of water to the roots. Once the layer hits two inches, warns Landschoot, roughly half of the lawn’s roots are growing in the thatch and can be choked off from water if the thatch dries out, leading to desiccation (bio speak for extreme dryness). Thick thatch can also create a veritable hotbed for insect overpopulation and lawn disease. And, if thatch is so spongy that the mower wheels sink down into it, you can find yourself inadvertently hacking off most of your leaf material.

It’s also just plain exhausting to remove thatch; you need a special machine to slice it vertically, then you have to rake and dispose of it. “All that,” sighs Landschoot, “is why people get all bent out of shape about thatch.”

The thing is, contrary to the long-held myth, grass clippings are not part of the potential problem.

Kemosabe Says…The Grass Clippings Aren’t to Blame

True, the laws of gravity are hard/pointless to argue. When you mow and let grass clippings fall into the turf, they may very well wind up down in the thatch. But Landschoot and Patton say most turfgrass scientists don’t consider the clippings to be part of the thatch, since they are short-lived and break down rapidly. So, there’s no need to worry about disposing of the grass clippings – they’ll degrade readily on their own.

Here’s the reason, straight from your grade school biology textbook. Because they are basically leaf material, grass clippings are mostly water (we’re talking 80-90 percent of their composition). Once said clippings dry out, very little biomass remains—and what does remain is so high in nitrogen that microorganisms will feed on that first. And why wouldn’t they? Grass clippings are easier to eat than thatch, since thatch consists of roots and stems, which are full of fibrous lignin.

To sum it up, if you dispose of your grass clippings in the trash to prevent thatch, as Landschoot points out “you’re doing a lot of work for nothing.” And…you’re missing the pretty great benefits found in letting those clippings lie.

Hi-yo, Don’t Dispose of Those Grass Clippings!

Not only does leaving grass clippings where they fall not contribute to thatch, but there are also several benefits to letting them be. (Cue inspirational theme song.)

Grass clippings are beneficial to both soil and turf, enthuses Patton. Because they can be easily broken down by soil microbes, grass clippings return important nutrients back to the plant, and contribute to soil health by providing a nutrient source for the microbes themselves. In laymen’s terms: You can spend less money buying fertilizer. Landschoot says his team’s rule of thumb is to cut fertilizer by as much as a third just by returning grass clippings to lawn, rather than disposing of them the old way. In other words: #tremendoussavings, #saynotooverfertilizing, #lawnmaster.

Even More Benefits of NOT Disposing of Grass Clippings

But a few self-righteous (and accurate) hashtags aren’t the only reason Patton says “leaving grass clippings on your lawn is a good thing.” It also keeps a lot of unnecessary bulk out of landfills—a large part of why states and municipalities across the country have banned grass clippings from trash pickup. According to the EPA’s Municipal Solid Waste page, yard waste comprised 13.4 percent of the waste stream in 2010.

Perhaps the greatest win, though, is that leaving grass clippings saves another precious commodity: time. The EPA Greenscape program page estimates that leaving clippings where they lie by using modern mowers can reduce mowing time by 30-40 percent.

How to Remain the Lawn Hero You Are

Concerned that leaving the clippings will damage your rep as the best lawn-keeper on the block? Both experts we talked with suggested ways to keep your image intact. It’s basically all about committing to your schedule and your mower.

Clumps may be more likely during periods of tremendously fast growth, but regular mowing will help keep the peace. Mow frequently—once a week when grass is growing fast—and keep the mower at a reasonable height of cut—between two to three inches in height depending on the grass species. If you do miss a mowing and have an uncomfortably high clump to no-clump ratio, then just go back over the yard with the mower to break up big clumps. (Personally, I hit the lawn diagonally from the first pass, to give it that baseball diamond look. My wife really appreciates that “cool” look, and so do my neighbors.) Both experts recommend a mulching or recycling mower, which breaks up the clippings into finer particles so clumping is less likely.

Another ticket to a neat lawn is to keep mower blades ready for action—by having them sharpened every year, advises Landschoot. “I’m not anal about my lawn,” he confesses. “I try to mow once a week and if I don’t get to that, then the next time I raise the mower height a little, and within two to three weeks, everything looks fine again.”

EcoMyth Outcome: Myth Busted

Leaving grass clippings on the lawn does not damage your lawn by contributing to thatch. In fact, there are some pretty great benefits to leaving clippings where they lie, including soil enrichment, nutrient return, and time and money savings.

What to Do With Your Mower’s Bagger?

So, if you’re not going to be disposing of your grass clippings in the trash any more, what are you supposed to do with your mower’s bagger attachment? Simple – hang it up for good in the garage, or just throw it out. What if you don’t have a mulching or recycling mower? (I honestly don’t understand why they still make non-mulching mowers.) Get one.

Thinking About Getting a New Mower? Think Battery-Powered

And, while you’re at it, make that new mower an electric, battery-powered mower.

First, you’ll no longer need to buy gasoline – a real benefit to the environment already, especially so, since gas-powered mowers don’t burn very cleanly, so are notorious polluters. (My old gas mower, after literally decades of service, put out quite a cloud of blue smoke at startup.)

Secondly, you’ll no longer need to buy oil for your mower, since electric mowers don’t use oil.

Another huge benefit is, you’ll no longer need that annual lawn mower tune-up (which required a little advanced planning, to avoid the Spring rush). That’ll save you at least $100 or more, and two trips to the mower repair shop. The only annual maintenance an electric mower needs is to sharpen the blade, which you can do at home, or have it done while you wait the next time you’re at the hardware store, or near a sharpening shop.

Ah, Peace and Quiet!

Electric lawn mowers are also much, much quieter than gas-powered mowers. If you’re like me, you just accepted the load roar of the gas engine as a necessary evil. Once you’ve switched to a battery-powered mower, though, you’ll notice and appreciate the peace and quiet (and not need to turn off the mower so see why your spouse is flailing their arms, trying to catch your attention from the deck).

If you used to wear the recommended ear protection when mowing, you can toss those ear muffs aside, and just enjoy the serenity of your own yard. Or, put in your earbuds and enjoy music or a podcast at a reasonable volume for a change.

One Green Thing You Can Do – Skip the Grass Clipping Disposal

Probably the easiest eco-friendly action ever: Just leave those grass clippings where they fall and reap the many rewards. And, save yourself the hassle of hauling all those grass clippings to the curb, for disposal in a composting facility, or worse – the landfill!

Less work, less cash spent on gas, oil, and fertilizer, and a more relaxing experience – what’s not to like?