Great idea, Why not go one step further?

I would have to imagine were talking home owners, can't envision a landlord permitting it.

Lay down a 6 inch layer of good top soil and plant real vegetation, then cleanup would never be a factor. (Poo makes great fertilizer for the grass)

I know a person who build a 20 x 20 all glass (greenhouse style) addition to her home, and filled it with potted trees so she could let 2 iguanas free roam in there.