The short answer is nearly anywhere, but not everywhere:

• You can’t put a moss wall outside in direct sunlight, or it will be scorched.
• You can’t put a moss wall up in a dry area. Moss walls require a minimum level of humidity to look good, about 40 to 50 percent.
• You shouldn’t put a moss wall near heating or air conditioning vents. The blasts of hot or cold dry air will ruin it.
• You can’t put a moss wall where it might get wet (near running water, spigots, sinks, fountains, etc.).
• A moss wall only protrudes out from the wall by two to three inches, so it can fit near any space.