Minecraft wiki entry for Huge_fungus, associated text: Both variants can grow instantly from their respective fungi if planted on its respective nylium block (e.g. warped fungus on warped nylium), and either a player uses bone meal on them, or a dispenser dispenses bone meal on them. There is a 40% chance of growth with each bone meal used. The bone meal is still consumed even if the huge fungus does not grow.