Best substrate to grow reishi mushroom | Reishi mushroom farming | Biobritte mushroom farming Best substrate to grow reishi mushroom. The substrate is the source of food for fungi. Note that the roots of a plant get food from the soil – which is the primary food source for the plant. Fungus, on the other hand, connects mycelium to the substrate to get food. The substrate is the primary source of food for fungi so they can produce mushrooms. When choosing the best type of substrate for your mushroom-growing project, make sure it is a match to the spawn you will be using. So, if you want to grow mushrooms on logs, it is best to use a wood-based spawn like sawdust or plugs. If the mycelium is already familiar with the spawning material, the time for colonization is reduced. Also, you need to consider the types of mushrooms that you want to cultivate. Mushrooms like reishi, lion’s mane, and maitake are best on wood-based substrates while other varieties like oysters thrive on alm