Putting Grass Clippings In Piles: Why It’s A Mistake To Do This!

The misconception of a good grass clippings compost pile

Grass clippings are organic materials that are very rich in nitrogen and decompose quickly after they are cut. When placed in a pile without care, the combined effect of compaction, the presence of moisture and the absence of oxygen generates a rise in temperature (70°C or more) which leads to the fermentation of the grass. Within a few days, the grass turns into a viscous ammonia jelly in the heart of the pile, which can become very smelly for the neighborhood.

In order not to get angry with his new neighbors, you will have to change the way he manages his grass clippings.

The good old mowing pile, is practical, but not recommended.

Managing grass clippings, 1st solution: balance the pile

To avoid bad smells, it is imperative that you mix his grass with an equivalent volume of carbon-rich materials (hard, dry and brown) such as dead leaves, pine needles, straw or shredded wood… This is to rebalance the C/N ratio (the proportion between carbon and nitrogen). It is up to him to organize himself in order to have enough of these elements, from spring to autumn, by storing them in advance near his pile.

Managing grass clippings, 2nd solution: mulch with fresh grass

Freshly mown grass is an excellent mulch rich in nitrogen, to be placed in the flower beds or the vegetable garden, quickly decomposed and assimilated by the plants. However, you should not exceed 3 cm thick layers to avoid the disadvantages of fermentation.

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Managing grass clippings, 3rd solution: dry the grass

The cut grass can be put to dry in small swaths of 30 cm wide and 15 cm high. Without any risk of fermentation, it can slowly dehydrate and be used after about ten days, as a thicker mulch (5 to 10 cm) or as a carbonaceous element in the compost heap, to balance, guess what… the grass clippings.


  • James Jones

    Meet James Jones, a passionate gardening writer whose words bloom with the wisdom of an experienced horticulturist. With a deep-rooted love for all things green, James has dedicated his life to sharing the art and science of gardening with the world. James's words have found their way into countless publications, and his gardening insights have inspired a new generation of green thumbs. His commitment to sustainability and environmental stewardship shines through in every article he crafts.

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