Minecraft wiki entry for Glow_lichen_farming, associated text: Because it can be fertilized by a dispenser, and it always goes to an open block off one of the four sides, it can easily be autofarmed by rapidly firing bone meal from a dispenser, and blocking off all available places to grow, except one, and monitoring that block with an observer connected to a dispenser with shears. The drops can then be collected by a minecart hopper below the block that the harvested plant is on.