Answer: Generally speaking, natural organic mulches will break down gradually and help to feed the soil over time, and molds are a part of that natural decay process. If the mold is excessive however, there are several things you can try. One is to fluff it with a rake to introduce air and sunlight, another is to avoid daily light waterings and instead be sure to water deeply but less often. If the mulch is very old you may want to simply top it off with a light layer of fresh mulch which should be less hospitable to mold growth than older mulch.
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