In this scene, Beatrice is in the garden near her 'sister'. This shows personification because the plant isn't a human but Beatrice loves it like a sister. There is also hyperbole in this scene because Giovanni thinks Beatrice is the most beautiful girl but it's only because of the flower.
Many times throughout the story, the author compares Rappaccini's garden to the Garden of Eden. This shows metaphor and possibly irony because the garden isn't that similar to the Garden of Eden.