Minecraft wiki entry for Tree, associated text: In order to grow a 2×2 tree (be it spruce, jungle or dark oak), four saplings must be placed adjacent to each other in a square. For growth to succeed, there must be no blocks adjacent (even diagonally) to the north-western side up to the final height of the tree. The bone meal can be used on any of the saplings. The largest jungle and spruce trees reach 31 blocks tall. Dark oak trees are typically 6–8 blocks tall.