Lawn grass clippings and compost: what’s the big deal?

Lawn clippings to add to the compost

Spring begins, and with it comes baskets and hampers full of lawn trimmings. What is one to do with all these clippings? Can you put lawn grass in the compost?

Well now, though it is possible to add your cut grass in the compost, there are a few rules to follow to get it done right.

Are lawn trimmings and compost compatible?

Yes, it’s possible to add cut lawn grass to compost, but there’s a ratio that shouldn’t be exceeded. Indeed, one of the most crucial advantages of compost is that it recycles a wide range of organic waste. You can’t properly compost something if there’s only a single type of waste.

Practically, since lawn clippings contain lots of water, putting too much of them at once in the compost would trigger rotting.

The rule of thumb to follow is that lawn grass shouldn’t count for more than 25% of what you add to your compost. Ideally, you’d even go the extra mile and dry the clippings out before throwing them on the pile.

Using lawn clippings in the garden

Compost that is well balanced with one-fourth of lawn grassThere are other ways to maximize all the great organic matter that cut lawn grass represents. As mentioned above, first of all, always try to top up that composter with the first few loads of the mower hamper, until you reach that fateful one-fourth limit. After that, another excellent use is to spread it atop the soil in your flower and shrub beds, and even in the vegetable patch.

  • A layer about an inch thick (2-3 cm) will break down and release nitrogen into the soil.
  • This plant mulch will stop and hinder weed growth.
  • Lawn trimmings also help lock moisture in the soil beneath it: you can only water every two or three days instead of doing it daily.

Mulching and topdressing, another way to use lawn clippings in the garden

Mulching with lawn clippingsMulching is indeed nature’s own way of transforming garden waste into healthy organic nutrients, and this works for the lawn itself, too. A thin layer of chopped up lawn grass will quickly break down and, in doing so, converts decaying matter into nutritious elements lawn grass needs to grow lush and dense. Watch out, though: if you plant on exclusively using the “mulch” position of your lawn mower to deal with lawn trimmings, you’ll have to mow the lawn at least twice a week. Mowing more than a half-inch of grass at a time is going to smother the grass growing beneath.

In the end, variety is the way to go: apply each of these methods in turn. From time to time, use the hamper to lug gras clippings to the compost, and then the next mowing session, mulch to leave shredded clippings on the lawn itself.


Credits for images shared to Nature & Garden (all edits by Gaspard Lorthiois):
Wheelbarrow with lawn trimmings by Ivan Radic under © CC BY 2.0
Compost mix by Andy Maguire under © CC BY 2.0
Vegetable garden prowess by woodleywonderworks under © CC BY 2.0