Minecraft wiki entry for Tree_farming, associated text: The wither makes it possible to auto-break blocks by using the wither's ability to break any blocks within a 3×3×4 area (4x6x4 on bedrock edition) of it one second after it has been damaged. The wither can be trapped in bedrock in any of the dimensions. Because of the larger breaking area on Bedrock Edition, you can grow oak, birch, jungle, acacia, spruce, and even dark oak (by using boats to shift the breaking area) inside the breaking area of the wither.