How to get rid of mold spores in bark mulch

Updated November 21, 2016

Mold spores are produced by mature fungi and released into the air. They are smaller than grains of pollen, easily passing through most normal filtering systems, including those naturally occurring in the human respiratory system. Inhalation of mould spores can lead to asthma attacks and sinus problems, particularly in those who are allergic to mould. Mold spores are often found in high concentrations near decaying organic material, making bark mulch a prime location for mould spore production.

Inspect the mulch. Make note of any areas in which mould is growing.

Place the sides of a large plastic garbage bag on either side of the mouldy bark. Push the bag beneath the affected wood, scooping up any mould in the process.

Seal the bag and place it in a hot, dry location until it can be set on the curb with the trash. Mold thrives on moisture, so dry or hot conditions will kill it.

Rake up the remaining bark mulch and dispose of it by placing it in plastic trash bags or by putting it in the compost heap.

Replace the bark mulch with mulching material less prone to mould growth, such as rubber, plastic, gravel, pine needles or straw.

Spread the new mulch 1 to 2 inches thick; deep mulching promotes fungal growth and development.

Turn the mulch over with a shovel at least once a month. This will expose the underside to fresh air and encourage adequate circulation, preventing the build-up of moisture on mulching materials.

Replace mulching materials regularly, completely removing the old material rather than simply adding new on top of the old. If any mould is growing, this will effectively remove it and prevent it from spreading.


If you have asthma, allergies or a respiratory disorder, don a protective mask prior to attempting to clean up or remove mould.

Things You'll Need

  • Plastic trash bags
  • Garden rake
  • Mulching materials
  • Shovel
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About the Author

Lisa Parris is a writer and former features editor of "The Caldwell County News." Her work has also appeared in the "Journal of Comparative Parasitology," "The Monterey County Herald" and "The Richmond Daily News." In 2012, Parris was honored with awards from the Missouri Press Association for best feature story, best feature series and best humor series.