I’m coming OUT!  OK, so vertical gardens on the exterior one moment and wallpaper the next.  Courtesy of Wall & Deco in Italy are these amazing options with OUT – Outdoor Unconventional Texture.  It would appear that you can only access most of their site by registering and logging in.  I’m waiting for them to confirm my registration (it’s not automatic), so I can get more info.

BTW – they have some amazing interior wallpaper as well :-)