Minecraft wiki entry for Witch_farming, associated text: In witch huts, witches are the only mobs that are able to spawn in the small area around a hut. Witch huts are one of the best places to farm witches, but they require spawning platforms and light levels of 7 or lower. One single witch hut can support a maximum of three spawning platforms. Witch huts spawn in swamp biomes, but the witch-exclusiveness depends on the entire hut being inside a swamp biome. Sometimes, the player can be extraordinarily lucky and have up to 4 witch huts within 128 blocks of a central point. This allows for 4 witch huts to be active at the same time.