One Million Trees by 2040: How Will Berlin Make It Happen?

The new tree law is out, the "how" is still a mystery. Heinrich Böll Foundation hosted a workshop to help figure it out and showcase existing planting and climate projects in Berlin.

Berlin’s new climate adaptation law is historic: it is the first comprehensive climate adaptation law on the city/state level (Landesgesetz). One million street trees by 2040, more green spaces and stronger protection against rising temperatures and extreme weather.

We attended a two-day workshop organised by Christoph Meyer, climate campaigner and educator, together with the Bildungswerk Berlin Heinrich Böll Foundation and talked with residents, activists and experts to explore what this transformation will look like in practice, how citizens can help shape it, and looked at the existing projects that have already been taking care of the city trees and building the infrastructure around it.

The Targets for 2040

The BäumePlus law grew out of years of work by the citizen initiative BaumEntscheid. The group developed a proposal for stronger urban tree protection and climate adaptation measures, pushing the issue into public debate and eventually reaching an agreement with Berlin’s government without requiring a referendum.

Dr. Christine Radomsky from BaumEntscheid walked us through the targets for 2040:

• Plant street trees across Berlin to reach one million by 2040

• Replace every felled tree with three new ones.

• Create 1,000 mini parks across the city.

• Introduce mandatory heat action plans in every district.

• Retain 50% of rainwater where it falls instead of sending it into the sewer system.

• Ensure a healthy street tree roughly every 15 metres on average.

• Cool Berlin’s 170 most heat-affected neighbourhoods, reducing temperatures during heatwaves by at least 2°C

Turning Plans into Practice

From December 2027, Berliners will be able to initiative the tree planting themselves. The questions still remain: who will be allowed to plant what and where? Who will control that it is done right? These criteria are still under development.

Christoph Meyer organises participants’ ideas

We discussed what citizens can already do before every part of the law comes into force. Ideas quickly covered the board: setting up and tending tree beds around existing street trees (for example, with Kiezgrün), connecting residents with professional landscape contractors, strengthening cooperation between researchers and neighbourhood initiatives, running public awareness campaigns, participating in the new oversight board, initiating protests, demonstrations and petitions against tree felling (such as many initiated by Baumentscheid here), and more.

The Work Starts in the Districts

Much of the law’s success will depend on what happens at the neighbourhood level. Berlin’s twelve districts have different approaches, resources and relationships with local initiatives.

Dr. Christine Radomsky compares how Berlin’s districts support grassroots initiatives

Charlottenburg-Wilmersdorf stood out as an example of particularly strong cooperation between residents, initiatives and the administration, including support with materials for neighbourhood planting projects.

Grassroots Tree Care

The field visits began at the Fritschestraße Initiative, where residents have created a model for community-based tree care. Working together with the Wassertanke initiative, the district administration and the BWB (Berlin Water Works), the team installed several 1,000-litre rain barrels that collect water for nearby street trees.

Hans Jürgen Zschäbitz presents the rain barrel and the planting beds in Fritschestraße

Although the rain barrel itself is technically simple, getting it installed was anything but. According to the co-founder Hans Jürgen Zschäbitz, the initiative only succeeded after years of repeatedly filing applications, returning to the district authorities and refusing to let the idea disappear. The lesson, he said, was to keep pushing again and again until progress is made.

Another simple but surprisingly effective design ideas was the Pinkelstein (pee stone) placed next to the deadwood border around the planting beds to protect the trees from the highly salt- and nitrogen-rich dogs’ urine. The project was a reminder that building a greener city is often less about expensive technology than about finding creative solutions to everyday urban problems.

Sponge City, One Block at a Time

The next stop was Baugruppe Moabit B27, a residential building completed in 2014 that demonstrates the principles of Berlin’s Schwammstadt, or “sponge city”.

The inner courtyard of Baugruppe Moabit B27, designed according to sponge city principles.

Instead of directing rainwater into sewer system, the site is designed to keep and store it. Permeable paving allows rain to soak into the ground, plants temporarily store heavy rainfall before it slowly infiltrates the soil, and green roofs retain water while reducing summer heat.

The group managing director Carsten Thiemann explained that the building was developed as a cooperative of residents who jointly planned and commissioned the project which allowed integrating sustainable features into the architectural design from the start.

A Miniature Urban Forest

The route continued to one of Berlin's newest Tiny Forests. Planted in 2024 by Kiezwald e.V., local residents and volunteers, the Moawald forest follows the Miyawaki method, a planting technique developed by Japanese botanist Akira Miyawaki. Trees are planted very densely: this way, they grow much faster, starting the forest creation process and capturing more carbon.

Tiny Forest Moawald

The workshop organizer Christoph Meyer noted that a 100-square-metre Tiny Forest could bind around 12.4 tonnes of CO₂ over time, with a significant share coming from the soil improvement process through the addition of humus and biochar.

The Spaces Still Waiting for Transformation

The final stop of the workshop showed a different side of Berlin’s climate adaptation challenge. At a parking place on Huttenstraße, we looked at the opposite of a sponge city: a large, fully paved area with no plants or shade. Using it as a starting point for discussion, we explored how commercial spaces could be redesigned. Ideas included adding more trees, replacing sealed surfaces or making them permeable, and improving rainwater infiltration.

The Work Ahead

We will keep an eye on how the law develops. In the meantime, we encourage you to support local initiatives with your time and donations, watering street trees with Gieß den Kiez, planting flowers or smaller plants around the tree with Kiezgrün or getting involved in reforestation projects like Bergwaldprojekt to start making Berlin greener today.

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