Mulching is a method of grass cutting where the grass chute is 'plugged' so the grass clippings are deflected back into the blade again and again until they are fine enough to bypass through and disappear deep into your lawn. Mulching mowers feature a special domed deck that is designed to increase the circulation of grass clippings.
Contrary to what you may have heard, mulching your lawn clippings does not promote nor increase 'thatch' in your garden. Thatch is produced from fibrous portions of the grass plant including the stem and root but not the grass blade. Clippings are part of the grass blade and retain 80-85% water. They decompose quickly. Thatch formation is enhanced when homeowners apply too much fertilizer or over-water their lawns causing excessive growth.
Another common misconception is that mulching promotes moss growth. This is not the case. Moss is a spore which will flourish in poor soil conditions such as in shady areas or around trees and hedges. Mulching will attack moss due to the nitrate and potash that the mulched clippings produce.
Many conventional rotary lawnmowers today are mulch capable. They come in a few different shapes and forms. Pedestrian rotary lawnmowers can be dedicated mulching lawnmowers or conventional lawnmowers with a removable mulching plug. The most popular mulch capable lawnmower is the Snapper ESPV21675, with a removable mulching plug.
Ride on lawnmowers today are mostly all mulch capable. They come in various forms from dedicated mulching and side discharge lawnmowers to front deck riders by Husqvarna. Conventional ride on lawnmowers like a Husqvarna TC138 with a deck mounted in the middle of the machine can also be made mulch capable by simply inserting or removing a mulch plug. Or alternatively conventional ride on lawnmowers can now come with a mulching flap fitted permanently on the machine. This flap is controlled by a lever near to the operater, meaning to switch from collecting to mulching mode you do not need to leave the seat. Popular ride on mowers with this built in mulcher include the Honda HF2417 and the Husqvarna TC338.