@jacqueline Oh my goodness, that's adorable! Waking up has never been nicer.
Could you put a hanging basket for stuff below the shelf, as long as he can't get to it from above?
I have a rectangular wire basket with sort of guide rails at the top that slide onto the shelf from below. It fills the space at the top of the middle shelf in my shelf unit.
There might not be enough space though. But I can't think of a way to add plants I'm afraid.
Your cat is very cute!