An artificial Jungle biome can be created by planting enough jungle grass in one area and letting jungle vegetation grow. Is there a safe way to do this without having enemies spawn? For example if I want a jungle grass farm, will I be safe if I just provide background walls and enclose all the jungle grass, or will the artificial biome extend beyond the walls and allow jungle enemies to spawn outside? How far would the artificial biome extend?
Note: This question is specifically about jungle but may apply to all biomes in general.
Best Answer
If you want to prevent enemies from spawning in a Jungle biome (artificial or not), build several houses and have NPCs move into them. This is the only reasonable way to fully stop hostile mobs from spawning in general.
Note that during Blood Moons enemies will still spawn, even with NPCs nearby.