Minecraft wiki entry for Bone_meal_farming, associated text: To create an automatic farm, stone generators are used to replace the platform that is converted to moss. A mechanism is required to break any moss carpet that grow on top of the moss, usually flowing water or pistons, as this would otherwise prevent any further stone from being converted beneath the carpet. The moss block and other plant items can then be collected and composted. A recycling system is also required to ensure that the farm is self-sustaining in bone meal.