Artificial underground jungle help.

[Vanilla Isis]

I am attepnting to create an artificial underground jungle biomes for spores and such and for some reason both times I have tried I just end up creating a surface jungle in a giant hole. Is there a specific way to do it, something I need other than depth, mud, and jungle seeds. For reference the latest failure I had was 100 blocks wide, 3 blocks deep on all sides 360' Undergound and was entirely covered in jungle grass and still only spawned surface jungle items and mobs

[kai. [VF4-A]]

Try making it in the Cavern layer.

[MilkJugz_2000]

try adding some types of walls - i made a cavern layer when i removed the jungle walls so probably the same vice versa

[Vanilla Isis]

Update. Madie it at 1150 cavern layer and it seemed to work. Thanks for the tip. What I cant figure out is why the wiki for artifiical biomes would say that anything below surface and not hell would work