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How to Get Rid of Mold From Mulch

Wood landscaping mulch is made of shredded wood and bark. Given time, microscopic bacteria and fungi cause the wood to decay. Slime mold, or Fuligo septica, sometimes referred to as "dog vomit mold," is one common fungus that can grow on decaying wood. The mold is unsightly but causes no harm to plants or animals. The best thing to do is to leave it alone and allow it to finish its cycle of decay. You can, however, take steps that may prevent the formation of mold on mulch.

Toss or rake the mulch. Do this every few days during periods of high humidity coupled with high moisture, such as after rainfall or watering. This may help prevent the formation of mold or stop it in its early stages.

  • Wood landscaping mulch is made of shredded wood and bark.
  • You can, however, take steps that may prevent the formation of mold on mulch.

Carefully remove mold if you prefer not to leave it alone. Beneath the mold can be spores that will spread. Because areas of mold are usually small, you can cover and scoop the mold with a plastic bag, such as a garbage bag. Push the sides of the bag beneath the mold, collecting the mulch along with the mold.

Dump the mold and mulch in your compost bin or close the bag and place it in the trash.

Rid Of Mold Spores In Bark Mulch

Bark mulch, whether natural or dyed, adds an attractive, finished look to the garden while keeping down weeds and holding in moisture. The benefits of an organic mulch are offset when consistently damp or too dry mulch develops mold and fungus or you buy it with mold spores already present. Use a material that allows for 1.2 pounds of available nitrogen per cubic yard of mulch. Breaking down the mulch, particularly that from fresh wood or younger trees, in a compost pile before you lay it in your garden also keeps the microorganisms that break down the mulch from robbing the soil and your plants of the nitrogen they need to grow. Spread mulch no more than 3 inches thick. Remove the fruiting bodies of any molds or fungi that develop with a small shovel to the compost pile or garbage. They include: slime mold, unpleasant-looking foamy patches of bile-yellow or pink that dry up and blow away if not removed; stinkhorns, upright red or orange finger-sized fungi with a smelly gooey brown cap; and bird's nest fungus, multiple tiny brown cups filled with tiny round spores.
Mulch from the bark of pine trees and hardwood bark mulch screened to remove particles smaller than 3/8 inch has fewer problems with mold and fungi than other bark mulches. Remove them if you have small, curious children.

  • Carefully remove mold if you prefer not to leave it alone.
  • Breaking down the mulch, particularly that from fresh wood or younger trees, in a compost pile before you lay it in your garden also keeps the microorganisms that break down the mulch from robbing the soil and your plants of the nitrogen they need to grow.
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