This might sound silly, but what about having a section of the vive just decked out in sphagnum moss? Either just the bottom or ontop of hides and whatnot, then add felt plants (or the more real-looking plants) all over so it gives the illusion that they're all real, while only the moss is?
The moss holds a tonne of moisture as well, so it's great for keeping uo the humidity!

It's the only thing I can think of that won't end with crushed plants

Best of luck! Feel free to post a photo of the end result, too!