Fern farming is a process of farming ferns by applying bone meal to existing ferns and mining the increased layer with shears.
Ferns do not have any use in the game, however they can be used for decoration. You can plant ferns and large ferns in plant pots or on grass to make a good aesthetic for a rustic or taiga-style build.
If you bonemeal a fern, it will grow in height, and it can then be mined with shears. The process can then be repeated, and that is it.
You can automate the system with a dispenser with bonemeal, a hopper minecart system to pick up the ferns and a minecart system to move the player around if a larger farm is built with more than one fern being bonemealed. A hopper clock can be used to dispense shears after the previous set of shears is broken.