Minneapolis Solid Waste & Recycling recommends that you not bag, but leave grass clippings on your lawn. Read on to find out why.
Ten Common Questions About
Leaving Grass Clippings on the Lawn
1. First I couldn't put my grass clippings in the garbage, now I'm supposed to leave them on the lawn. Why?
Grass clippings contain valuable nutrients that your lawn needs to grow. Throwing them in a landfill was expensive and a waste of landfill space. State law banned grass clippings from landfills and incinerators in 1990 in the metro area.
Unfortunately, about half the yard trimmings set out for collection in Minneapolis are grass clippings. That means we spend nearly a million dollars a year just collecting grass clippings – grass clippings that could enrich our lawns.
2. Is it good for the grass to leave the clippings on the lawn?
Yes. Remember, your lawn is a garden of grass plants, not a rug, and it needs nutrients to grow. Grass clippings left on the lawn will eventually decompose and recycle nutrients back into the soil. Leaving the clippings on the lawn for a whole year is equal to about one annual fertilizer application. In addition, leaving the grass clippings on the lawn also helps shade the soil, keeping the roots cooler and reducing moisture loss.
3. Won't my lawn be drowning in grass clippings after a while?
Not if you mow often enough. Short grass clippings – an inch or less in length – decompose quickly. During the spring and early summer you will probably have to mow more than once a week. Your grass will also benefit from more frequent mowing. Removing more than one-third of the grass plant when you mow leaves the grass less resistant to disease and the stress of hot summer weather.
4. Doesn't this mean I'm going to have to spend more time mowing?
Not necessarily, you might even spend less time mowing. Lawns mowed at the proper height with a sharp blade will mow quickly and easily, and you won't be stopping to empty the bagger into bags and hauling the bags to your curb or alley. Remember, you also "spend time" at your job working to pay for bags, and fertilizer. Don't forget this when determining how "long" it takes you to bag the grass clippings.
5. That sounds fine except in spring when I fertilize and the lawn grows like crazy. What do I do then?
Over fertilizing in the spring can result in rapid grass growth and a less healthy lawn. Apply about 1/3 of your annual fertilizer in the spring and 2/3 in the late summer and fall. Fertilizing in the late summer and fall will help build up the roots for a healthier lawn and reduce the rapid spring growth. Using a fertilizer which releases nitrogen more slowly can also reduce rapid spring growth.
6. Don't I need one of the new mulching mowers I heard about?
The new mulching mowers do a nice job of chopping up the grass clippings, but you don't need a new mower, just follow the instructions in #3 above.
7. Can I use any mower to leave the clippings on the lawn?
Some mowers are unsafe to operate if you just remove the bagger. Check your owners manual or talk to an authorized dealer before removing any bagger. In some cases, an adapter kit is required. Be safe and check it out.
8. Should I ever collect my grass clippings?
In some situations collecting the clippings makes sense:
- If the grass is too long or wet, the grass clippings can clump and damage the lawn.
- If your lawn is diseased, removing the clippings may help reduce the level of disease.
- If your mower is unsafe to use without a bagger, collect the clippings.
9. What else can I do with my grass clippings if I have to collect them?
Grass clippings can be used for weed control. Place a layer of grass clippings one to two inches deep on top of the soil around garden plants, flowers, shrubs or trees. This is called mulching. Not only will mulching hold down weeds, but it will also keep moisture in the soil. Don't use more than an inch or two because you'll reduce the flow of air and water to the soil. As the grass clippings decompose, they will enrich the soil.
Grass clippings can also be used in composting. Grass clippings added to other garden plants or leaves will help speed up the composting process. Adding a large amount of grass clippings to your compost bin at one time may require more frequent turning to prevent odor problems. Call Minneapolis Recycling at (612) 673-2917 for a free brochure on how to compost at home.
10. What if I have been spraying my lawn with a broadleaf weed killer?
The best choice is to leave the grass clippings on the lawn. A second choice would be to compost the clippings. In a properly managed compost pile, herbicide residues should break down during the composting process. To avoid harm to your plants, wait 3 to 4 weeks after applying a weed killer before using grass clippings as mulch.
Before you use a weed killer, consider that weeds are opportunists. A weak, thin growing lawn is an open door for weedy plants to move in and get established. Healthy grass that is properly mowed, fertilized, and watered will out compete many of our common lawn weeds.
This brochure is largely based upon "Ten Common Questions Often Raised Regarding Grass Clippings" authored by Robert J. Mugaas and published by the Minnesota Extension Service.
Last updated Jan. 13, 2012