Minecraft wiki entry for Time-saving_tips, associated text: Tip: Growing giant mushrooms above ground can be tricky, because mushrooms cannot be planted (and will uproot after a short time) if the sunlight level is too high. A workaround is to use a few dirt blocks to make a dark hole shielded from direct sunlight, place an ordinary mushroom inside the hole, then quickly remove the dirt and apply bone meal before the mushroom has time to uproot.