Filter Variants: Optimization metrics and filtered station observations for maize (Zea mays, DWD Plant ID 215) in Germany

This dataset provides two complementary outputs of the PhenoPhaseR processing pipeline (https://doi.org/10.5281/zenodo.18743008) for maize (Zea mays L., DWD Plant ID 215), covering the 9 DWD-reported phenological phases modelled by the pipeline for the entire territory of Germany for the period 1993–2024. PhenoPhaseR is an open-source R workflow that couples the PHASE model - a growing-degree-day (GDD) approach with adaptive outlier filtering - to derive spatially consistent, quality-controlled point observations of phenological phase-start dates from the DWD volunteer observer network. The dataset components provided here correspond to processing Steps 5–6 (filter variant optimization) of the seven-step pipeline.