grass cuttings, almost without exception, should be mulched back into the grass. The advantages of mulching grass clippings are much too many and important to overlook. Mulching grass clippings makes sense for a variety of reasons, including supplying nutrients to the soil and saving time and money. grass clippings, like mulching leaves into the grass in the autumn, give vital organic matter to the soil.
How to Mulch
Mulching is best done using a mulching mower, which is similar to any other mower with a few exceptions. Mulching kits are often provided as an option when purchasing a mower, although any mower may be simply adapted. Special “mulching” blades with more cutting surfaces are used in combination with additional baffles underneath the mower. To trap the clippings under the deck, the outflow or chute is stopped. The baffling moves the clippings about inside the mowing chamber, allowing them to be cut many times and blasted into the lawn’s surface.
Effects on Thatch Growth
A common misconception is that leaving grass clippings on the lawn causes thatch—a dense layer of dead and living grass shoots that forms a mat between the soil and grass blades. But grass clippings do not cause thatch buildup. Clippings consist mostly of water, and the remaining tissue is quickly broken down through microbial activity. Grass clippings may add to an existing thatch problem, but as long as the lawn is mowed regularly and a mulching mower is used, mulching lawn clippings into the lawn will not cause thatch buildup.
However, clumping of grass clippings may occur when you mow under wet or over-grown conditions. Care should be taken to avoid clumping and address it when if it occurs in a thick enough later that can potentially smother the grass. This generally happens only if you mow a lawn that has been allowed to grow too long, or if you mow it when it is wet. Either way, clumping is easily remedied by raking up the grass clumps if they occur.
Think of the effort and resources involved in dealing with lawn clippings. Collecting them with a mower. Dumping into piles or more bags. The removal and disposal. Repeatedly emptying the grass collection bag. The time and labor involved in removing clippings is significant, especially if you consider how beneficial clippings are for the lawn.
Recycling grass clippings onto the lawn may give up to one pound of nitrogen to the lawn’s yearly needs. Because a normal lawn requires up to four pounds of nitrogen per year for optimal development, returning the clippings to the lawn may essentially eliminate one complete fertilizer treatment, saving time, money, and work. Worms, beneficial bacteria, and fungi quickly consume clippings, boosting the variety and activity of the complicated food web.
The overall goal of an organic or natural-based lawn care program is to achieve 5 percent organic matter in the soil, and most lawns have an organic matter ratio of only 2 to 3 percent. It can take years of topdressing with compost, mulching leaves, and recycling grass clippings to increase the organic matter by even one percent, so there is no better time to start than now.
If the soil biology advantages aren’t enough to persuade you to mulch grass clippings back into your lawn, maybe the financial benefits will. A lawnmower collecting system is significantly more costly than a mulching equipment. The more clippings that are handled, the more work is required. A collecting system must be emptied, and the clippings must be placed someplace, either on-site or hauled away. Even though these additional processes do not raise the total cost of a lawn care service, they do contribute to labor, fuel, and equipment maintenance expenditures.
If clippings are trucked off-site, where do they go? Tipping fees may be involved if they are taken to recycling facilities. If they are kept on-site and used in a home compost pile, care must be taken with regards to pesticide usage, since chemical pesticides can contaminate compost.
When to Avoid Mulching
- It is a good idea to collect clippings rather than mulching them back into the lawn if there are an abundance of weeds such as dandelions and crabgrass. Collecting the clippings around the time the weeds go to seed may help reduce the spread of weed seeds throughout the lawn during certain times of the year.
- If the grass has gone unmowed for more than a week due to rain or another reason, it may be best to gather the clippings or, at the very least, mow over the clumps multiple times to better spread them.
- If chemical insecticides and synthetic fertilizers have been used repeatedly on a traditionally managed lawn, clippings may not degrade adequately. Insecticides used to prevent grubs, for example, may kill many more than the target pest and leaving a grass almost dead. Synthetic fertilizers raise soil salt levels, which may impair soil life. The absence of microbiological activity and earthworms may limit the quantity of decomposition required to break down grass clippings.