The Greenhouses

• Type: Herbology classroom buildings
• Location: On the grounds of Hogwarts School of Witchcraft and Wizardry, near the vegetable patch
• Owner/Residents: Hogwarts School of Witchcraft and Wizardry; managed by the Herbology professor (e.g., Pomona Sprout)
• Key Features: Glass-walled structures, magical climate control, housing a vast collection of mundane and magical plants

The greenhouses are a series of numbered glasshouses located on the Hogwarts grounds, used for the study of Herbology. From the outside, they appear as simple glass structures, but their interiors contain a wide variety of magical flora, some of which require specific and magically-maintained environments to thrive. The air inside is often described as warm, damp, and smelling of earth, damp soil, and fertilizer. Different greenhouses are used for different year levels and house plants of varying difficulty and danger. For instance, Greenhouse One is used for first-years, while Greenhouse Three contains more dangerous plants for older students. The greenhouses are a fundamental part of the Hogwarts curriculum, providing the necessary ingredients for Potions and teaching students how to handle and utilize magical vegetation. They are under the care of the current Herbology professor.

The greenhouses serve as a key location for both lessons and significant plot developments throughout the series.

• In Harry Potter and the Philosopher's Stone, Harry's first Herbology lesson involves learning about Devil's Snare. This knowledge proves vital when he, Ron Weasley, and Hermione Granger later encounter a giant Devil's Snare while protecting the Philosopher's Stone.
• In Harry Potter and the Chamber of Secrets, the greenhouses play a central role. Students are taught how to re-pot baby Mandrakes in Greenhouse Three. These same Mandrakes are later used to create the Mandrake Restorative Draught, which cures those who have been petrified by the Basilisk.
• In Harry Potter and the Goblet of Fire, Harry meets Cedric Diggory near the greenhouses, where Cedric advises him to take the Golden Egg into the bath to decipher its clue for the Second Task of the Triwizard Tournament. Harry also witnesses a suspicious conversation here between Igor Karkaroff and a figure he mistakes for Severus Snape.
• In Harry Potter and the Half-Blood Prince, Professor Slughorn acquires valuable Venomous Tentacula leaves from the greenhouses for his private Potions stores. Later, Harry uses a feigned visit to the greenhouses as a pretext to speak with Slughorn after Aragog's death, which leads to him finally obtaining the crucial memory about Horcruxes.
• In Harry Potter and the Deathly Hallows, during the Battle of Hogwarts, Professor Sprout, Neville Longbottom, and other students use plants from the greenhouses as weapons, throwing Mandrakes and other dangerous flora over the castle walls to attack the invading Death Eaters.

• Greenhouse One: Used for first-year students. Lessons here cover relatively basic (though still potentially dangerous) plants like Devil's Snare.
• Greenhouse Three: Used for second-year students and above. It houses more advanced and perilous plants, including Mandrakes, Venomous Tentaculas, and Puffapods. The lesson on re-potting Mandrakes takes place here.

For the film adaptations of Harry Potter and the Philosopher's Stone and Harry Potter and the Chamber of Secrets, exterior shots of the greenhouses were filmed at The Alnwick Garden in Northumberland, England, adjacent to Alnwick Castle. For later films, a permanent greenhouse set was constructed at Leavesden Studios. (film)