Compost With Mold: Why Does The Compost Mold?

Unfortunately, when caring for the compost inexperienced gardeners often make a few mistakes. So it happens that the compost is attacked by flies or mice, or even mold. What should you do if there is mold in the compost?

Mold is natural in compost


Mold bacteria are found in all garden soil and, of course, in compost. The bacteria contribute to decomposition and are therefore an important component in the cycle of composting.
If severe mold growth occurs, it is an indication of improper filling of the composter. Most likely, you have layered in too many moist materials.

Mold is especially common if you put away a lot of moist grass clippings at once. The grasses cannot rot as quickly if they are not mixed with other materials.

What to do if there is mold in the compost?
Basically, you don’t have to do anything. The mold will eventually break down and make a good humus.

If the sight bothers you a lot, there are several ways to make it invisible:

  • Rearrange compost
  • move compost
  • mix wet and dry materials well
  • mix in bark mulch or paper
  • fill in worms
  • mix in old compost
  • use compost starter

Some gardeners also simply add a few shovels of garden soil over the moldy surface.

Make compost rot faster

If you have composted a good mixture of different materials, the decomposition process will be quite rapid. There is then hardly any mold to be seen. If you do not have enough different materials available, add worms to the compost.

See also  When And How To Apply Compost?

Giving compost accelerators is also helpful. You can buy these accelerators at garden supply stores. or easily make your own from yeast, water and sugar.

If you have an older compost pile in your garden that is already well rotted, simply add a few scoops of this old compost to the moldy compost and dig it under a bit. By doing this, you will provide it with microorganisms that will ensure the compost decomposes.

Moldy compost is especially evident when you compost bread scraps. The bread always molds before it decomposes. Without this process, decomposition cannot take place.


  • 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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