I can put it outside , but how the dickens do I fasten it to the door? 
I've got a white UPVC door (so no nails)
I don't think I could use one of those door hook things (I wouldn't be able to close the door)
I've got one of those clear rubbery/plastic hooks that you can stick on. But it tends to fall off. I usually use it to hold an ivy and ribbon wreath but it's really lightweight.
My previous wreath was on the path 99% of the time.
The only thing I can think of is a thin ribbon (don't know how I'd fasten it inside the door though) But it would fit over the top of the door.
Any ideas?
TIA 