Device (1) for watering plants which is intended to be fitted to a growing container, such as a pot. The device comprises an external casing (2) intended to be placed inside the growing container and to be at least partially buried, said casing (2) delimiting a housing (3) having an open top end (4) intended to protrude from or lie flush with the soil, and a bottom end (5) having a passage (6) in the soil. The device further comprises a water reservoir (7) positioned inside the housing (3) and having an orifice (8) around which a water diffusion system (10) is removably mounted. The diffusion system (10) is designed to pass through the passage (6) of the casing (2).
