Not sure what you mean by European closets? In Britain just about every house has a traditional shrubbery pantry where we grow plants like herbs, small vegetables and such things and is also where we tend to keep small pets like hamsters, rabbits and haggises but I don't know what they do in the rest of Europe.
Should I ask my British girlfriend about this or will I look nuts?
I think I'm going to ask her regardless for her reaction.