Cumulus is a watering can in the form of a cloud that alerts when a plant needs watering by lighting its coloured rainbow handle. Via an arduino controlled sensor, it detects the moisture level of a plant soil and signals when it becomes dry. It is a cheap, open source, physical interface between children and nature. Cumulus is an educational toy made to spark conversations and interactions between parents, grand-parents, children and plants. This watering cloud will tell its surroundings whenever the plants needs water in a playful way. Based on the water cycle, it can be used as a basis for environmental awareness education. Small and affordable, it is a democratic tool to help parents. It allows them to start a conversation on nature, the environment, and the importance of water. The toy will be sold with a small booklet explaining the water cycle.