To bag lawn clippings or not to bag, that is the question
In today's "Growing Together" column, Don Kinzler says let the grass stay put when you mow. The research says it's best, and it'll save you time and money.
Could I interest you in free money every time you mow your lawn? I’ll even show you how to get your mowing done in one-third less time.
These claims sound like a cheap infomercial, but instead they’re based on near-unanimous turfgrass recommendations from our country’s leading research universities. And it all starts with a simple question: Is it better to bag lawn clippings while mowing, or not?
Those who do prefer to use a bagger attachment on their lawn mowers to collect the grass clippings usually feel it gives a better appearance to the newly mown grass. Some believe catching the clippings prevents a buildup of thatch in the turf.
There are obvious reasons to at least occasionally bag clippings, such as when the lawn has gone too long between mowings, and the clippings would lay on top like a newly cut hayfield. Such grass, if left on the surface, can easily smother and damage the lawn, and it's better bagged or raked off.
Granted, there are reasons for catching and removing grass clippings while mowing, but there’s overwhelming evidence that lawns become healthier if the clippings are allowed to filter back into the turf, instead of bagging and removing. Nearly all research universities have published recommendations strongly in favor of discontinuing the practice of bagging and disposing of clippings, in favor of recycling the material back into the turf.
Discontinuing bagging is gaining in popularity, supported by a national movement called “Don’t Bag It,” started by Texas A&M University to promote the benefits of letting the clippings fall. You might say it’s a grassroots movement that’s catching on with homeowners. A term has even been coined — “grasscycling.”
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Behind the non-bagging concept is the science showing that grass clippings provide benefits to the turf if allowed to filter back in, rather than removal. The concept was enhanced a number of years ago when recycling-type mowers were introduced, with a blade that chops clippings finer, and aids in sending them downward instead of discharging through a side chute.
Recycling mowers and blades work well, but grasscycling can be accomplished with a side-discharge mower. Most clippings, if an inch or so in length, will filter downward, and it’s not recommended to be removing more than that length at one time anyway.
The following are benefits of allowing grass clippings to remain in the lawn:
- As grass clippings decompose, they release nutrients back into the soil, which can satisfy 25% or more of the lawn’s fertilizer needs, replacing one or more yearly fertilizer applications.
- The nitrogen from grass clippings has been demonstrated to be absorbed by grass plants in as little as two weeks after mowing, according to University of Connecticut research.
- Grass clippings are 80% water, so decompose rapidly without contributing to thatch buildup.
- The decomposing clippings add organic material to the soil, encouraging beneficial soil microbes and reducing soil compaction, creating a healthier soil and root zone.
- Increased organic material helps grass roots stay cool and moist with less soil evaporation, conserving water and requiring less frequent irrigation.
- The layer of decomposing grass clippings helps suppress weed growth.
- Lawns are less likely to turn brown during hot, dry weather, with a protective layer of decomposing clippings moderating the soil.
Remember the free money I mentioned? The above benefits reduce fertilizer and water costs, putting money back in our pockets. And mowing in one-third less time? University of Missouri studies show the average mowing time can be reduced by over 30% when you don’t bag the clippings and haul them to a yard waste collection site.
There’s another good reason for not bagging clippings. If grass has been treated with weed-killing herbicides, many such products persist in the clippings, such as the active ingredients dicamba and triclopyr.
If these clippings are taken to yard waste collection sites for disposal, these long-lasting chemicals can contaminate the compost that is eventually made and distributed for garden use. Such clippings can also damage plants if used as a surface mulch in the vegetable garden. Returning the clippings back into the turf while mowing solves the problem of disposal.
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Don Kinzler, a lifelong gardener, is the horticulturist with North Dakota State University Extension for Cass County. Readers can reach him at firstname.lastname@example.org or call 701-241-5707.