You’ll want to use untreated hardwoods like oak, maple, or poplar for growing shiitake mushrooms. Avoid using wood from evergreen trees or treated lumber, as these contain resins and chemicals harmful to mushroom growth.
Select logs or lumber that are free of pesticides and not too fresh – age them for 6-12 months first. Hardwoods offer the right nutrients and conditions for shiitake mycelium to thrive.