Fertiliser

• Type: Magical Substance, Herbology Supply
• Owners: Not applicable to a single item; used by various individuals and institutions, including Professor Sprout, Rubeus Hagrid, and Horace Slughorn.
• Maker: Sourced from natural, often magical, origins.

Fertiliser in the wizarding world consists of various substances used to enrich soil and promote the growth and potency of magical and mundane plants. These substances are a cornerstone of Herbology and are frequently derived from magical creatures. Known types include:

• Dragon Dung: This is a common and effective fertiliser. Rubeus Hagrid kept it in large barrels to help grow his giant pumpkins. When dried, it is also a key component in the production of Dungbombs.
• Mooncalf Dung: Described by Horace Slughorn as a “wonderful fertiliser,” suggesting it is highly valued and perhaps rarer or more potent than other varieties.
• Compost: A general term used by Professor Sprout for the material used when re-potting Mandrakes, indicating that standard organic decomposition is also used in magical horticulture.

The primary purpose of fertiliser is to provide essential nutrients to magical flora, which may have far more complex or demanding needs than non-magical plants.

• Horticultural Use: Its main application is in Herbology to cultivate plants successfully. Rubeus Hagrid used Dragon dung to grow his pumpkins to an enormous size for the annual Hogwarts Hallowe'en feast. Students in Professor Sprout's classes use compost and other fertilisers to care for plants in the Hogwarts Greenhouses. The potency of different fertilisers varies, with some, like Mooncalf dung, being particularly prized.
• Alternative Uses: Certain types of fertiliser have applications beyond agriculture. Dried Dragon dung is a primary ingredient in Dungbombs, a popular joke product developed by Fred and George Weasley for their shop, Weasleys' Wizard Wheezes.

The use of magical creature by-products as fertiliser is a well-established practice within the wizarding world. Its importance is evident in its routine use in the Herbology curriculum at Hogwarts and by accomplished wizards like Horace Slughorn, who actively sought out rare ingredients like Mooncalf dung. The trade and collection of such materials are an integral part of the magical economy surrounding Potions and Herbology.

Fertiliser serves as a key world-building element that adds practical depth to the field of Herbology. It establishes a tangible link between Care of Magical Creatures and Herbology, showing how different magical disciplines are interconnected. Mentions of fertiliser often help to develop characters. Rubeus Hagrid's use of Dragon dung highlights his comfort with large, dangerous creatures and his rustic, hands-on approach to his duties. Horace Slughorn's procurement of Mooncalf dung reinforces his personality as a collector of rare and valuable magical ingredients. Finally, its use in Dungbombs is a perfect example of the mischievous and inventive nature of Fred and George Weasley.

• In the video game Hogwarts Legacy, Fertiliser is an expanded magical tool. It can be used to instantly increase the yield of a plant when it is harvested. It can also be deployed as a combat item, where it functions like a hostile, sentient plant that attacks nearby enemies (video game).