Since 1.0.4, there is a normal jungle on the surface above the Underground Jungle, so you don't need to go deep to grow it.
What you can expect depends on how deep you go. The depth that Underground Jungle enemies (Hornets and Man Eaters) and Jungle Roses need seems to have been increased in patch 1.0.4; I'm not sure of the exact height, but it's possible that it's world specific, like the Dungeon position.
I built a working Underground Jungle grinder before 1.0.4 right below the zero feet mark. The only monsters that spawn now are Jungle Bats and Snatchers (the over-ground jungle enemies). Jungle Roses won't grow, and ones that grew before the update don't drop anything.
Whether you need to trim the vines, depends. They don't stop monster spawns, at any rate. You could also build a stone ceiling above each layer to prevent the vines from growing at all.