When we look in our Peterson Field Guide to Wildflowers, we see that the wallflower is classified as a late bloomer. But given plenty of water, sun, and socialization with other creatures (especially outgoing ones, like the social butterfly), they can blossom at a young age—say fifteen years or so?
Maybe it's because of his repressed memories that Charlie retains a somewhat wide-eyed, child-like view of the world in The Perks of Being a Wallflower. Charlie's freshman year of high school is a life-changer, though. After being introduced to drugs and alcohol, meeting some of the best friends he may ever have, and discovering some dark secrets within himself, Charlie is definitely about to grow up.