One way to get the oysters to grow after the bag is depleted is to let them drop spores onto pieces of corrugated cardboard. Once the cardboard is nice and dusted by spores you layer them in between straw or some sawdust. Like a cardboard straw sandwich. Then you put a humidity tent over the layers and keep everything humid and around 70 - 80 degrees. Eventually you will see white myceleum growing on the cardboard and they will begin blooming into mushrooms. The hardest part is keeping green mold or other fungi from taking over, fairly difficult.