Berlin App Turns 900,000 Trees Into Virtual Pets

What if caring for your neighborhood could be as simple and rewarding as caring for a pet?

That's exactly what's happening in Berlin, where an app called "Gieß den Kiez" (Water Your Neighborhood) lets residents adopt and water city trees. Since launching in 2020, it's turned urban forestry into something closer to a video game, with thousands of people now tending to the city's 900,000 street trees.

The app works beautifully in its simplicity. Open it up and you'll see a map of Berlin dotted with GPS pins, each representing a real tree. Trees desperately needing water glow orange or red, while well-hydrated ones stay green. Adopt a tree and the app sends you personalized watering instructions based on the tree's species, age, and current weather conditions.

"It feels very fun, almost like a video game," says Amanda Gläser-Bligh, who adopted a linden tree she named Linda. "I think many people may want to water the trees, but they might feel weird about doing it. But if you have this app encouraging you, you know it's the right thing to do."

The app launched during COVID lockdowns, when Berliners were desperate for reasons to get outside and connect with nature. That timing proved perfect. CityLAB Berlin, the team behind the app, made it open source, meaning any city could adapt it for free.

Berlin needs its trees now more than ever. This summer, temperatures soared past 103°F. Trees don't just provide pleasant shade anymore. They're lifesaving infrastructure that can drop neighborhood temperatures by several degrees on scorching days.

The science backs this up. One American study found that U.S. counties with better tree cover spend less on healthcare. Australian researchers discovered that communities with healthy tree canopies showed better mental health outcomes than those without.

The Ripple Effect

What started as one city's creative solution is now spreading across Europe. Potsdam, Leipzig, Magdeburg, and even Paris's 17th arrondissement have launched their own versions using the open-source code. Each city now has residents competing to keep their virtual pets happy and their real neighborhoods cooler.

The app also maps every public water pump and tap, making it easy for tree adopters to find water sources. It's urban planning that puts power directly in residents' hands.

Beyond temperature control, these adopted trees clean the air, provide nectar for city bees, and offer visual relief from concrete and advertising. They're transforming how people think about public space, turning anonymous street furniture into something personal worth protecting.

Thousands of Lindas are getting the water they need, one caring neighbor at a time.