Poison ivy will grown anywhere. If the Gotham bad guys have any brains, they'll plant it around their hideouts or lairs or whatever they call their bad guy den. Makes the skulking and spying really dangerous and potentially uncomfortable. I bet Alfred keeps lots of oatmeal bath salts and soap on hand.
I know I would, if I were a Gotham bad guy. Although maybe Batman's one of the lucky few who aren't allergic to the stuff.