Minecraft wiki entry for Block_and_item_duplication, associated text: The mechanism for growing giant spruce trees is known to be glitched in JE 1.16 snapshot. Instead of growing a giant tree on the saplings, the game grows the tree on the first position where space is sufficient and a dirt block is present in the north-west position. When the tree is grown, all the dirt blocks are filled in. With bone meal and piston automation, a semi-auto dirt duplicator can be produced (YouTube by ilmango).