The Hogwarts Greenhouses

• Type: Herbology Classrooms and Plant Nurseries
• Location: On the grounds of Hogwarts School of Witchcraft and Wizardry, behind the castle
• Owner/Residents: Hogwarts School of Witchcraft and Wizardry; managed by the Herbology Professor, primarily Professor Sprout
• Key Features: A series of glasshouses containing a vast and varied collection of magical and mundane flora, some of which are extremely dangerous. The greenhouses are magically maintained to suit the needs of the plants within.

The greenhouses at Hogwarts are a collection of numbered glass buildings used for the instruction of Herbology. They are located on the school grounds, past the vegetable patch. The air inside is typically described as warm, damp, and smelling of rich soil and fertiliser. There are at least three known greenhouses, each housing different types of plants based on their level of danger and the curriculum for different year groups. For instance, first-year students have their lessons in Greenhouse One, while second-years use Greenhouse Three for more challenging plants like Mandrakes. The greenhouses are essential for cultivating ingredients for the Potions curriculum, with professors like Horace Slughorn known to harvest valuable components like Venomous Tentacula leaves directly from them. They are a fundamental part of a Hogwarts education, teaching students how to care for, utilize, and defend against a wide array of magical plants.

The greenhouses feature consistently throughout the series as the primary setting for Herbology classes and are central to several key plot points.

• In Harry Potter and the Philosopher's Stone, knowledge of Devil's Snare gained from a lesson in the greenhouses allows Hermione Granger to save herself, Harry Potter, and Ron Weasley from the plant guarding the trapdoor to the Philosopher's Stone.
• In Harry Potter and the Chamber of Secrets, the greenhouses play a critical role. In Greenhouse Three, Professor Sprout teaches the second-years how to re-pot young Mandrakes. These same Mandrakes are later used to create the Mandrake Restorative Draught, which is the only cure for the victims petrified by the Basilisk of Salazar Slytherin.
• In Harry Potter and the Goblet of Fire, students learn to handle Bubotubers, and Harry has a significant conversation with Professor Sprout near the greenhouses about Cedric Diggory's courage.
• In Harry Potter and the Half-Blood Prince, Harry witnesses Professor Slughorn conversing with Professor Sprout as he collects Venomous Tentacula leaves for his private stores. This interaction is where Harry first attempts to retrieve the true memory about Tom Riddle and the Horcruxes from Slughorn.
• In Harry Potter and the Deathly Hallows, during the Battle of Hogwarts, the greenhouses serve as an armoury. Under the direction of Professor Sprout and Neville Longbottom, students hurl Mandrakes, Venomous Tentaculas, and other dangerous plants from the battlements to attack the invading Death Eaters.

• Greenhouse One: Used for first-year Herbology lessons. It houses less dangerous plants suitable for younger students, such as Devil's Snare.
• Greenhouse Three: A greenhouse used for more advanced students, including second-years. It contains more dangerous and sensitive plants, most notably the screaming infant Mandrakes. It is explicitly stated to be a different greenhouse from the one used in the students' first year.
• Other Greenhouses: The existence of numbered greenhouses implies a series of them, likely containing progressively more dangerous, rare, or N.E.W.T.-level plants. Professor Sprout is mentioned tending to “some of the more dangerous plants out in the back of greenhouse three,” suggesting dedicated spaces for highly volatile flora.

• In the film adaptations, the greenhouses are depicted as ornate Victorian-style structures made of glass and iron. The interior sets were built at Leavesden Studios. (film)
• The video game Hogwarts Legacy features a large and detailed greenhouse complex that players can freely explore, containing numerous interactive plants from the wider Wizarding World. (video game)