European grasslands rank among the most species-rich ecosystems globally, supporting exceptional plant and animal diversity while delivering key ecosystem services. Yet, these habitats are increasingly threatened by both land-use intensification and abandonment. Effective public policies are crucial for maintaining grassland multifunctionality but face a critical obstacle: the lack of harmonized, high-quality baseline vegetation data. Using Switzerland as a case study, we identify key data gaps and systemic shortcomings that hinder ecological research and policymaking. Despite Switzerland’s nationwide farmland biodiversity monitoring programme, its recent implementation leaves a vacuum of long-term reference data. We highlight six priority areas for action: (1) improving the availability and resolution of land-use, soil, and climate data; (2) ensuring full and standardized metadata with consistent taxonomies; (3) enhancing access through dataset indexing and open publication mandates; (4) addressing sampling and observer biases through coordinated, multi-scale surveys; (5) supporting field logistics and fallback site planning; and (6) securing long-term institutional commitment to monitoring. These tools are essential for adaptive policies at national and European scales that sustain grassland biodiversity.