This dataset documents vascular plant diversity recorded on grassland sites in Germany. Vegetation surveys combined (i) a full inventory within one 2 m × 2 m quadrat per 50 m × 5 m sub-transect, where species cover was estimated, and (ii) an additional 30-minute search for further species across the entire 5 m × 200 m transect, recorded as presence only. Cover was assessed using an adapted Braun-Blanquet ordinal scale with predefined percentage ranges; mean cover per species was derived from the midpoint of the assigned range. Because vegetation layers may overlap, summed covers can exceed 100%. Species were identified in the field; records marked "cf." indicate uncertain species-level determination. Plant nomenclature follows the German standard list, supporting harmonized taxonomic reporting. The dataset includes sub-transect dimensions, survey method, observation area, scientific names, cover class, associated percentage ranges, derived mean cover, and taxonomic uncertainty flags. Data were collected at multiple restored and reference grassland sites across Northern, Central, and Southern Germany in 2022 and 2023, with site coordinates reported at two-decimal precision (blurred for privacy).