Cities are broadly defined as the absence of nature, as places with only hardscapes and humans. This false dichotomy does a disservice to urban centres and humans. PopUP Forest provides immersive nature experiences that amplify grassroots efforts to build a more sustainable and resilient urban future. PopUP Forests help stake out policy and investment in biodiversity, greenspaces and ecosystem services. These localized activations are green spaces that support wildlife, delight urbanites and then disappear, weaving nature into the everyday lives of city dwellers, pushing politicians on ecologically informed policy and helping to mainstream biodiversity globally.