Oyster grain spawn can be used to inoculate dowels for log culture or to inoculate substrate for fruiting. A wide variety of substrates can be used as a fruiting medium. Some of our favorite are coffee grounds, wheat straw, hardwood sawdust/wood-shavings and cardboard. This 4 lb bag of grain spawn comes sterile in a sealed bag with a micro filter patch. Grain spawn is best used fresh but can be stored for short periods in a refrigerator.