The study of magical plants and how to take care of, utilize and/or combat them. Herbology lessons are shown in each of the first six books. Being located in greenhouses on the grounds, trips to and from Herbology lessons are written to depict the weather at the time. There are at least three greenhouses described in the books, holding a variety of magical plants of varying degrees of lethality, including mandrakes, bubotubers and Snargaluff pods.

The subject is depicted as closely related to Potions, due to the nature of the plants, many of which are cultivated for extracting useful ingredients.