Wow, I have not paid much attention to the teacher until now, but his stock went up a lot in my eyes since he recognized the student’s good work. Nice one, sensei. I aim to be someone like you.
He works so hard on something so ostentatious as flowers with their bright colors and vivid displays, with the fundamental irony being that he's never able to be noticed by anyone but the girl who has a crush on him. There's some kind of contrast there that I like where something so inconspicuous can cause something so beautiful to bloom without anyone ever realizing it.
I want to say it's a metaphor, but for what I'm not sure. Probably love, I'd guess.