In the beginning, there were sheep.
Then came scythes, reel mowers and, finally, the familiar rotary mower, cutting grass with blades like a low-flying helicopter.
Despite the progression in technology, a close-cropped lawn - if it is mowed by anything but sheep - is threatened by thatch, which is a matted layer of dead grass clippings that accumulates at the soil line.
Thatch blocks water and air from getting into the ground, and builds on itself, slowing decomposition of subsequently cut grass.
Enter the mulching mower, a rotary mower whose blades keep the clippings airborne for a while, flailing them around and chopping them up, before dropping them back on the ground. The small pieces decompose quickly enough to avoid the problem of thatch buildup.
Although you can avoid thatch buildup with a conventional mower by cutting frequently or collecting the clippings, all this is extra work.
Collecting clippings also deprives your lawn of certain benefits. Decomposing clippings become food for earthworms and other organisms that aerate the soil. Eventually the clipping turn to humus, which helps nourish the lawn and soaks up moisture to hold between rains or waterings.
Either purchase a mulching blade to fit your present rotary mower, or go out and buy a bona fide mulching mower.
In many respects, buying a mulching mower is just like buying a conventional lawn mower. Things to consider include width of the deck, ease of adjusting the cutting height, and, of course, cost.
Perhaps the most important option to consider is whether the machine is powered by electricity or gasoline. Electric mowers have the edge for weight, quietness and low maintenance, and they start with the flick of a switch. Recent breakthroughs in battery design have led to the development of electric mowers powered by rechargeable batteries.
Another consideration is whether a mulching mower can be set up with a grass catcher. You might, after all, want an occasional load of clippings for garden mulch, or to add some high nitrogen fuel to your compost.
Mulching mowers work best on grass that is neither wet nor too long. If the grass has grown too long for good mulching action, collect the clippings or else go over the lawn with two or three successively lower passes.
The best you can do for your lawn is to mow in a timely manner to the correct height, then let the clippings fall back to the earth. Ideally, such clippings are chopped fine and spread evenly - which is what a mulching mower does best.