Minecraft wiki entry for Pumpkin_and_melon_farming, associated text: This farm packs high yield per growing space in a small tile area per growing space (2x2, excluding border and water). All mechanical and circuitry components are above ground and stem level, so the ground can devote to maximize growth rate. Its stacking height is 6 blocks. This design might be bad because the crops aren't picked up by the hopper when they fall on the full dirt blocks.