Forum:Artificial jungle wont spawn trees!

Ok, basicly i made a Glass greenhouse with mud in it and planted jungle grass seeds, it however was too small and nothign spawned, so i made it about 3 times as wide, now it is spawning all surface monsters as it should correctly including pirnhas in the water at the top, however, no matte rhow long i go away and leave it for, there are never any trees when i come back to it (Yes i make sure that the grass is left to grow).

So the only problem im left to assum is the the layers are too low for any treest to grow, Could sum1 please help me out and let me know if any1 can confirm this?

Here is a screenshot of the greenhouse: Jungle_Greenhouse.jpg

Any help on this matter would be much appreciated, Really badly trying to get a source of trees without having to replant acorns all the time as ive used around 30 stacks today and cleared every single tree in the actual map generated jungle 3 times aswell as both corruption areas >.<

Thanks in advance to any1 who can input =]

Jess