Regular lawn mowing helps keep your lawn healthy and looking great. For the healthiest lawn, cut only one-third the length of the grass blade each time you mow. This leaves enough blade for health photosynthesis and not so much that the lawn appears ragged. Mowing produces grass clippings, which decompose to provide nutrients for your lawn. Both regular lawnmower blades and mulching blades produce these clippings, though the clippings will look different depending on the type of blade.
Regular lawnmower blades cut the grass with one stroke. The rotary action of the turning blade blows the grass clipping out the side of the mower, or into a grass catcher bag. A mulching blade curves more. It cuts the blade of grass once, then throws the cut piece back into the blade to be cut several more times. This results in a lot of very small pieces of cut grass.
Lawnmower blades of all types work best when sharp. Dull blades tear and shred the grass, resulting in a ragged-looking lawn and irregular chunks of cut grass instead of small pieces. Sharpen both regular and mulching blades with a metal file or sharpening stone, following the curve of the blade and maintaining about a 40-degree angle between the sharpening file and the edge of the blade. Keep the blade balanced and don't bend it. Sharpen blades at least twice every mowing season, or whenever you notice them becoming dull.
If you routinely bag your grass clippings, you don't need a mulching blade. Cut grass can be added to a compost piles or used as one of the layers in a lasagne-style raised bed garden, in which layered organic matter serves as both soil and mulch. If you like to leave your grass clippings on the lawn, a mulching blade chops the grass into smaller pieces that decompose more quickly, returning nutrients to the soil faster than grass cut with a non-mulching blade. Mulching the lawn with grass this way may also allow you to use less water and fertiliser, since the mulch holds in moisture and returns nutrients to the soil.
Mulching Blade Tips
Keeping your grass a little longer hides the scattered clippings better. How long you keep the grass depends on the type of grass. If you've let the mowing go and find your lawn is so long you'll need to cut more than one-third of the height of the grass blade in order to get the grass to the length you desire, cut the grass in stages. Set the mower to cut about half the length the first pass, then lower the blade and cut again. Your mulching blade will do a better job of cutting the grass into small, uniform pieces with this method. If the mulch gets too thick, you can rake and bag some of it.