Grass Clippings as Mulch?

I don't use grass clippings as mulch in my gardening recipes for several reasons.

  • Topic: Mulch
  • Author: David Salman
  • Keywords: grass, mulch, compost, Mulch, grasses
  • Date: June 2002

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Judging by some of the return e-mails regarding my remarks in May’s HCG E-Zine, there are more than a few gardeners who use grass clippings for mulch and are proud of it! Well, as they say, “different strokes for different folks.” Just as there are many different recipes to cook the same dish, many gardeners use their own favorite gardening techniques and design ideas to create their gardens.

I don’t use grass clippings as mulch in my gardening recipes for several reasons.

  1. Green grass clippings can compress into a slimy layer and create a water and air impermeable mat over the top of the soil. This can smother the soil and result in a lack of oxygen and water for the roots below.
  2. Grass clippings are very “hot” and require a lot of heat and nitrogen to break them down. This is not a process you want happening around your growing plants.
  3. And lastly, If you use herbicides (including “weed and feed” fertilizers) and fungicides on your lawn I feel there is a danger involved when recycling these clippings. These clippings may have residual chemicals and it’s not a good idea to put this back around your garden plants. This would be especially ill-advised when used to mulch your herb or vegetable plants!

If you thoroughly compost your grass clippings in with some other coarse organic materials like shredded leaves and finely chopped twigs and branches they will make a suitable mulching material. Composting clippings will help to breakdown these garden chemical with the help of soil microbes during the composting process. Adding the coarse materials helps fluff the grass so water and oxygen get through to the soil more easily. Maybe the answer is to do more composting before using grass clippings as yard mulch.