Greenhouse Three is where second-year and subsequent-year students take Herbology. There are “far more interesting and dangerous plants” in this Greenhouse than in Greenhouse One (CS6). It is kept locked; Professor Sprout has the keys (CS6). When Harry first comes near the Greenhouses he notices “a whiff of damp earth and fertilizer, mingling with the heavy perfume of some giant, umbrella-sized flowers dangling from the ceiling” (CS6). There is “a trestle bench in the centre of the greenhouse” (CS6), In Harry’s first lesson of second year, Sprout laid out ear muffs on this bench for the students to use when they replant Mandrakes.