Summary Phenology – the timing of seasonal biological events – is a sensitive indicator of climate change and ecosystem dynamics. Long‐term, broad‐scale phenological data are crucial for understanding and predicting plant responses to environmental change. However, until the mid‐2000s, European phenological observations were scattered across national networks, limiting large‐scale analyses. In response, the Pan European Phenology (PEP725) database was established 15 years ago as an open‐access, reference‐grade infrastructure for plant phenology data. PEP725 unifies observations from over 30 countries, compiled from 1868 through the present, with all records standardized to a common protocol. The database now contains more than 13 million phenological records for c. 265 plant species across 46 phenophases, making it the world's largest repository of ground‐based plant phenology data. We highlight key scientific insights and cross‐sector applications enabled by the dataset, and share technical lessons learned. Looking ahead, we outline a roadmap for PEP725's evolution – including new data contributions, technological upgrades, global integration, and community engagement – to ensure it remains a vibrant, open community resource driving phenology science forward. We invite the plant science community to utilize, contribute to, and further cocreate this phenological data platform.
Templ et al. (Thu,) studied this question.