Grass clippings are the shredded leaf material left behind after mowing. Homeowners must decide whether to collect these remnants (bagging) or leave them on the turf to decompose (grasscycling). This choice significantly affects the lawn’s health, maintenance time, and environmental impact. The appropriate practice varies based on the lawn’s current condition, the length of the clippings, and specific maintenance goals.
Why Leaving Clippings Is Usually Best
Leaving grass clippings on the lawn is the recommended practice because it cycles valuable nutrients back into the soil. This process, often called grasscycling, serves as a natural fertilization method. Clippings contain significant amounts of nitrogen, phosphorus, and potassium, which are the same nutrients found in commercial lawn food products. By leaving them in place, the turf can receive up to one-third of its annual nitrogen requirement from this recycled material.
Clippings are composed of approximately 80% water and are easily broken down by soil microorganisms. They decompose rapidly and do not contribute to the buildup of thatch. Furthermore, the thin layer of clippings acts as a natural mulch, helping the soil retain moisture. This moisture retention keeps the root zone cooler and reduces the rate of water evaporation, conserving water during hot, dry periods.
Specific Situations Requiring Bagging
Bagging becomes necessary when the volume or condition of the clippings threatens the lawn’s health or appearance. The most frequent reason to bag is when the grass has grown excessively long between mowings. Experts recommend removing no more than one-third of the grass blade length in a single cut. If more is removed, the resulting long clippings can mat together, forming thick clumps that shade and smother the underlying turf.
Bagging is also necessary when the lawn shows signs of fungal or bacterial disease. Diseases like brown patch or dollar spot can spread when infected clippings are redistributed by the mower. Collecting and removing these clippings interrupts the disease cycle, preventing the dispersal of spores to healthy areas. This practice should continue until the disease is fully under control.
Another instance for bagging is when noxious weeds have gone to seed, such as crabgrass or dandelions. If the mower chops up weeds with mature seed heads, it effectively broadcasts thousands of new seeds across the entire lawn. Bagging ensures these viable seeds are collected and disposed of, mitigating the risk of a widespread weed infestation. Temporary bagging is also beneficial before specific maintenance tasks, such as applying a granular pre-emergent herbicide or prior to overseeding to ensure better soil contact.
What to Do with Bagged Grass
Once collected, clippings should be utilized or disposed of thoughtfully, as they represent a valuable resource. Grass clippings are highly nitrogen-rich, making them an excellent “green” material for a backyard compost pile. Because of their high nitrogen and water content, they must be mixed thoroughly with “brown” materials, such as dried leaves or wood chips. A ratio of about 2-to-1 brown to green is recommended to prevent the pile from becoming slimy and anaerobic.
Clippings can also be used as a garden mulch to suppress weeds and conserve soil moisture around ornamental plants or vegetables. Apply them in a thin layer, generally no more than one or two inches deep, and ensure they are dry before application. Applying thick layers of wet clippings causes them to mat, restricting oxygen and potentially creating foul odors. If the clippings were bagged due to disease or herbicide application, they should not be used as mulch or compost and must be disposed of according to local municipal yard waste regulations.