Millet is an ideal grain for mushroom cultivation and can be used for making mushroom spawn or as a substrate supplement. Millet has a much lower endospore load than rye and wheat, making it less prone to contamination. And its small size means your spawn will have many more inoculation points for the same volume of grain. By using millet, the mycelium will spread more evenly and abundantly through the substrate. And, as a high-nutrient medium, it also encourages rapid mycelial expansion. Storage: Millet is best stored in a cool, dry place. Because the grains can easily absorb moisture, we recommend storing in food-grade, air tight containers.