The technique of enhancing species diversity by spreading species-rich green hay following turf scarification was tested in a semi-improved meadow site in Cumbria, UK. Botanical assessments were carried out in May 2008 (prior to treatment), May and October 2009, and May 2010. Both total species-richness (number of species per m2) and the richness and aggregate cover of positive indicator species were enhanced by hay spreading, with an average of 21·8 species per m2 compared with 17·0–18·7 species per m2 for other treatments by May 2010. Significant increases in all three variables occurred by May 2009, with even greater increases between this assessment and May 2010. Hay spreading introduced seven new species, most of which subsequently increased over time, and enhanced the frequency of a further seven. All these species together accounted for only about 5% of vegetation cover in 2010, but the level of species-richness achieved was equivalent to that of good quality semi-improved grassland and also equivalent to that achieved in studies where the technique was developed. Results are discussed in detail in relation to the seeding phenology of species at the donor site, as are other factors affecting the technique's potential and possible means of enhancing it.