Citizen science shows local flower diversity, not landscape composition, drives flower‐visitor diversity in experimental mini‐meadows in gardens

Pollinator populations are declining globally due to habitat loss, including in highly urbanized and intensively farmed regions like Belgium. In Flanders (northern region of Belgium), private gardens make up 13% of the land, suggesting that enhancing floral resources in people's gardens could considerably benefit flower‐visitors. As part of the citizen science project ‘FlowerPower Your Garden’, a species‐rich grassland of 6.75 m 2 was installed in 485 garden lawns. The participating citizen scientists then monitored floral resources and flower‐visitors over three consecutive years. The study had two main objectives. First, to assess the reliability of citizen science data through expert validation in 27 gardens in 2023. Second, to investigate local and landscape drivers of flower‐visitors in gardens using both the expert‐collected and citizen‐collected data of the three project years 2022–2024. Validation revealed a significant positive correlation between expert‐ and citizen‐collected flower‐visitor richness, while citizen scientists slightly underestimated flower‐visitor species richness. Nevertheless, the clear correlation between citizen science and expert datasets suggests that the data are robust enough to support additional analyses of the three‐year citizen scientist dataset in this study. From the citizen‐collected data, we conclude that 69% more flower visitor species were observed in June than in August. Flowering plant species richness in the experimental grassland plots had a significant positive effect on the flower‐visitor species richness. In contrast to our expectations, the proportion of semi‐natural habitat had a significant negative effect, and open unbuilt space did not influence species richness of flower‐visitors (in a 1000‐m radius). Temperature during the measurement had a significant negative effect on the flower‐visitor species richness in the citizen‐collected dataset. These findings highlight the value of citizen science for large‐scale pollinator monitoring and underscore that increasing local floral diversity in private gardens is a key effective strategy to enhance their ecological value.