With many designs in the marketplace, lawnmowers discharge grass clippings into either side or rear catcher bags. You may want to discharge the clippings onto the lawn, however, by removing your lawnmower's catcher bag. Although removable for maintenance and replacement, a catcher bag always must be used with a rear-bagger lawnmower unless the mower is equipped with a plug or plate over the rear opening.
Bagging for Safety
A lawnmower's sharp blades cut grass and create an air flow that moves grass clippings out of the machine's lower deck and through a discharge opening. Removing a rear-bagger lawnmower's catcher bag uncovers the discharge opening, which faces directly at your lower legs as you operate the machine. Depending on the mower's engine power, clippings exiting the discharge opening can strike your legs at high speeds, possibly causing injuries. Moving parts are often visible through the discharge opening, too; do not place any body part near a discharge opening that is not covered. Maintain overall safety by reading your mower's operator's manual to find safe alterations to the rear bag.
Mulching Grass Safely
The only time a rear-bagger mower should be operated without its catcher bag is after it is converted to a mulching machine. Conversion kits are available commercially. Such a kit is used to make a standard lawnmower mulch grass clippings and redistribute them across the yard. Instead of making one cut, a converted mower chops grass into 1/4- or 1/2-inch lengths that drop easily to soil. A typical conversion process involves removing the catcher bag and adding a conversion kit or plug at the mower's clipping discharge opening. Kit designs vary, but a typical design forces clippings to remain with the mower until they fall from the mowing deck as mulch. Avoid mowing wet grass, however, because the resulting clumping hinders the cutting process and may cause the lawn's surface to form a mat. Wet conditions significantly reduce a mower's power as well, but a mower cuts dry vegetation cleanly.
Benefiting Lawn Health
Thatch, which is decomposing foliage and stems, accumulates across a yard over time. Although it may seem that adding grass clippings to your lawn accelerates thatch buildup, the clippings actually decompose quickly, adding critically needed nitrogen to soil. Microorganisms respond to that nutrient influx by breaking down grass clippings and benefiting the soil with aeration and increased nutrients for roots to uptake. Using an approved mulching conversion kit for your mower is essential if you want to benefit your lawn with clippings. Simply dumping grass in clumps across the yard does not speed decomposition but hinders grass' photosynthesis ability and growth potential.
Collecting Those Clippings
If thatch is thicker than 1/2 inch, or if grass is wet, then keep the catcher bag attached to your rear-bagger lawnmower, and refrain from mulching clippings. Instead, use the collected clippings as mulch by spreading them under plants, or add them to your compost pile. Adding wet grass clippings to a lawn, especially when thatch is thick, contributes to thatch growth because the clippings cannot decompose into the soil. The clippings can be used in various garden areas instead of sent to a landfill as yard waste.