A process for preparing artificial bed blocks for "Shiitake" mushroom cultivation, comprising culturing lumps of spawn (mycelia) in a bottle or other containers, taking out the grown-up mycelia from the container to be kept in a closed space, keeping culturing while raising humidity in the space close to saturation to form a new aerial hypha layer on the whole surface of the lumps of spawn for higher resistance to weed fungi, then sprinkling with water over the lumps in open space to prevent weed fungi from depositing.
