Most semi‐natural grasslands are threatened by invasive alien plants, which have also overgrown abandoned fields. We conducted a 6‐year experiment testing different methods of eliminating invasive Solidago species and adding seed to restore valuable species‐rich grassland. Three removal treatments (herbicide spraying, rototilling, turf stripping) and two seed addition methods (direct sowing of a fast‐growing grass species mixture, spreading of fresh hay collected from a semi‐natural meadow) were examined alongside control treatments (no removal, no seed addition). The experimental plots were mowed twice a year, and the vegetation composition, biomass production, hay chemical composition, and fodder quality were assessed. Mowing twice a year significantly reduced Solidago cover. Although significant differences were observed in the invaders' cover between the removal treatments and between the seed addition methods early in the study, the differences lessened over time, especially for the removal treatments. By the end of the 6‐year study period, the Solidago cover was reduced to 25% of the initial complete coverage. Spreading fresh hay greatly reduced Solidago biomass and yielded the highest characteristic species cover. Herbicide treatment was no more efficient than the more environmentally friendly methods over the study period. The results suggest that fresh hay is good method of seed addition for restoring old fields overgrown by invasive Solidago. With mowing of the restored area twice a year for several years, Solidago removal by turf striping (scalping) followed by the spreading of fresh hay is recommended for grassland restoration given its environmental impact, cost, and hay quality.