Giess den Kiez maps over 900,000 Berlin trees and flags those urgently needing water

The interactive platform Giess den Kiez has mapped more than 900,000 trees across Berlin and calculates how much water each tree needs, allowing residents to organise watering efforts around the city. The project runs on open‑source software so other municipalities confronting summer heatwaves can adopt the same model.

Developed by Sitilab Berlin, the platform estimates water requirements using a tree's age, species and recent local rainfall. An interactive map uses colour codes to mark trees that are in critical need of watering; users can also see when a tree was last watered and register their own watering activity.

Young saplings, which lack the deep root systems of older trunks, require more frequent irrigation to survive. The platform also provides practical guidance on proper watering technique, rainwater collection and lists locations of public water pumps in the city.

Volunteer network and municipal support

The initiative began in 2020 and currently counts 12,000 registered volunteers. Their work supplements municipal green‑space services that cannot always meet demand during increasingly hot summers.

The largest annual peak in citizen watering — nearly half a million litres poured — occurred after the platform’s launch in 2020 during the pandemic, when people sought ways to spend time outdoors and connect with nature and community. Watering surges during heatwaves: on 27 June, when Berlin recorded a historic temperature of 39.9 degrees, residents poured 8,000 litres of water over trees across the city.

Photo: SitiLab)