Minecraft wiki entry for Jungle_tree, associated text: 1×1 jungle trees require a 3×3 column of unobstructed space at least 5 blocks above the sapling to grow (6 blocks including the sapling itself). Additionally, 1×1 jungle trees require 5×5 layers without obstruction for the top 3 layers of its final height. No horizontal clearance is needed at the base of the tree (a sapling planted in a hole 1 block deep still grows).