It's not surprising that the season of blossoming, freshness, and wonder would make an appearance in a poem about intellectual curiosity and a young girl's coming-of-age. In the final stanza, we actually see the "fruit" of Mrs. Long's care: the speaker as a confident, intelligent, and unafraid girl who looks optimistically to the future.
Giovanni's use of spring here relies not just on these set ideas about the season. She's also making reference to C.S. Lewis's book The Lion, the Witch, and the Wardrobe. In lines 46-50, she invokes the wardrobe that acts as a portal to the wintry world of Narnia, which is ruled by the evil White Witch. In the end, the main characters vanquish the White Witch and spring returns to the land.
Mrs. Long also gets to do some heroic things for Giovanni—by supplying her with books that she normally wouldn't find at her library and by opening a door into the best version of the world that she knew. The result? Giovanni tells us that "no lions or witches scared [her]," that she moved forward fearlessly to a future full of promise. Is there a better way to pay tribute to a librarian-mentor? We think not.