|"Neither can live while the other survives..."|
Dragon dung fertiliser is a solution used to help Venomous Tentaculas and (presumably) other plants grow. Its main ingredient is Dragon dung, the potion's namesake. In 1997, Horace Slughorn asked Harry Potter to brew some in order to collect the otherwise unvaluable leaves of a Venomous Tentacula. The fertiliser is also noted to be Professor Sprout's preferred type.
- Harry Potter and the Half-Blood Prince (video game) (First appearance)