If you build 2x2 jungle or "Mega Spruce Trees" and then one block free to all sides then the trees will crow but if you set fences after that free block so the trees wont grow up.

That situation is very strange sometimes the trees will grow with fences.

Dark oak trees will grow every time with fences after one free block.

All wikis says that we need only one free block to the next block for growing up and that the trees will destroy fences if they are in the growing way.

Have added screenshots