As a matter of fact, there is. Take your favorite type of moss. It can be wet, or dry. Pop it in a blender with a lil bit of Dechlorinated water and make a slurry. Paint that slurry onto your background and as long as you keep it moist and the humidity stays up, you'll have lush moss all over in a few months.
Education is the most powerful weapon we can use to change the world ~ Nelson Mandela