Welcome to the forum. Um she's just probably loving the plant, I'm taking it as this is the only real plant in there. Usually they will hang out on it. Just to make sure, did you clean it well and remove all the dirt? If you didn't, then I would forcably find your frog. That fertilizer can kill your her. But if you cleaned it well and rinsed it, I would just let her be. She's loving her new green friend.