What is Mulching and How is it Done?
Overview
Mulching is a way to send small, chopped-up grass cuttings back into the turf instead of side-discharging or bagging the cuttings. The goal is to leave the cuttings in the turf and still have a healthy and attractive lawn. In order to achieve this, during the Summer periods when grass is growing rapidly you need to mow quite frequently (at least twice per week) so as not leave excess cuttings on your lawn.
Timing Recommendations
Mulching is best done during the slow-growing period between mid-to-late July and late-August. Since the lawn is impacted by heat and lack of rain, which reduce lawn growth, one can mow at more regular, weekly intervals and mulch the cuttings. We recommend bagging during rapid-growth periods for a more manicured appearance. We recommend mulching during slow-growth periods to get that extra bit of nutrients into the lawn from the cuttings as they decompose, along with the freedom from emptying grass catcher bags.
How to Mulch
To perform mulching, you install a mulch plug to cover the side discharge outlet and "seal" the mowing deck. On most mowers this can be done without removing the side discharge flap. Generally, you install mulching blades. Many recent tractors from brands such as Husqvarna and Craftsman come standard with mulching blades, which are perfectly suitable for bagging clippings as well. Check to find out if your machine came equipped with mulching blades. If not, remove the standard high-lift blades (used for bagging) and install mulching blades according to the instructions in your mower’s Operator’s Manual.
Install the mulch plug in place of the chute that goes to the bagger. You can remove the chute alone or the entire bagging system when mulching. Once the deck is sealed, when you mow, the cuttings are circulated inside the mowing deck and chopped up several times by the rapidly turning blades. Mulching blades more readily enable the chopping of cuttings.
The typical mulching blade has a longer, compound cutting edge. Essentially, it has two or three edges that extend from a point closer to the center of the blade out to the edge of the blade as compared to a traditional high-lift blade with one three-inch cutting edge that is intended to push the cuttings upwards into the bagger chute. With three cutting edges, the edges starting at the inside of the blade are set at three angles: level, downward (raised at the front), and upward (raised towards the rear for lift). With the cutting edges in this configuration, the grass cuttings are pushed in different directions for repeat cutting by the rapidly spinning blade’s varying edges. Since the deck is sealed, ultimately the cuttings are pushed back into the turf. As the cuttings decompose, they serve as a low-level fertilizer for the lawn.
When Can I Mulch?
Now, if you do not mow the lawn frequently enough, you cannot mulch. During rapid lawn growth, you will probably have to mulch at least twice per week. The reason is that you cannot mulch if you cut more than about 1/4 of the grass blade at a height no greater than 3.0-3.5 inches. In other words, when mulching you have to be cutting only a small portion of grass off the top in order to push it back into the lawn. If you try to mulch anything more than a 1/2"-3/4" inch cutting, you are likely to clog up the mowing deck and not spread cuttings properly. So, mulching is something you might do during part of the season, perhaps when the grass isn't growing very quickly (mid-summer) allowing you reasonable intervals between mowing sessions. During high-growth periods, you will have a nicer-looking lawn if you bag the cuttings, i.e., sending them out the chute into the grass catcher bags.
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