Minecraft wiki entry for Mushroom_farming, associated text: The main danger in small mushroom farming is that they must be low-lit indoor rooms, which poses the risk of hostile mobs spawning in the same area (except on Peaceful mode). This can be countered in several ways. The easiest way is to place copious numbers of soul torches, as they emit light level 10, which is dark-enough for mushrooms and lit-enough to prevent mobs. Another way is to place normal torches two blocks above from where you want your mushrooms to grow (sometimes in tiny holes cut into the ceiling overhead). Another way involves making the farming area just one block high and paving any walkways with slabs and using a water system to channel the mushrooms out of the farm room and into a collection point. This removes most of the danger, since mobs cannot spawn on half-blocks or in one-block-tall areas and any other areas can be lit up. The Nether is a safe place to start a mushroom farm, since mobs there will not spawn in small spaces.