There’s a lot of different advice out there surrounding the topic of whether one should mulch when mowing their lawns or catch the grass clippings to dump them on the compost heap.

What is mulching? Mulching is when lawn clippings are dispersed and left on the lawn as opposed to being collected in the mower catcher.  Many modern lawn mowers come with a mulching function in addition to having a catcher. Many people advise that mulching and returning the clippings to your lawn will return valuable nutrients to the soil, where as some people advise that doing so will form a “thatch” of dead grass that will smother your lawn and, leave it prone to disease.  The truth is, both of these statements are correct, and so the question becomes not “should I mulch” but “when should I mulch?”

Lawn grasses need nutrients and leaving the clippings on the lawn reduces the depletion of said nutrients, thus reducing the need for adding fertiliser. It also helps to protect the soil from extreme temperatures, and it holds in moisture. However, leaving too many clippings on the lawn can smother your lawn grass and create conditions for diseases to flourish. Thatch build up begins when organic debris builds up faster than it can be broken down.

So what’s the answer? Mulch only when you are trimming your lawn.  Cutting small amounts of grass off the top produces small clippings that will easily fall through the grass all the way to the surface of the soil.  Being small they will also be easily broken down and absorbed by the soil. The general rule of thumb is that you want to be mulching when your lawn is less than 7cm long.

Do not mulch when your lawn is over 7cm long as quite a lot needs to be cut off (although you should never cut your grass by more than 1/3rd of its total length).  Instead you should collect the clippings in your mower catcher and either compost them, or dispose of them. Such long clippings will smother your lawn and take much longer to break down, this in turn will cause a build up of thatch, and when moist, will be a welcome habitat for fungi.


Speaking of thatch, when deciding whether or not to mulch you should also examine the current state of your lawn.  If your soil is bare then set your mower to mulch and trim 10-15mm off the top. If the thatch is thick then we advise dethatching with a fine toothed rake or a dedicated dethatcher if you’re dealing with a larger section.

If you aren’t sure which option is best for you or if you would rather outsource the work so you can free up more of your valuable time, get in touch with the Lawn Squad, we are happy to get the  job done without any hassles!

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