Festulolium is an interspecies hybrid of meadow fescue and Italian ryegrass and its economic importance still grows. But quality of sowing material is often not acceptable. Germination ability often doesn’t even reach 75%. This paper presents the results of experiment aiming Festulolium seed quality improvement. There were found high correlations respectively between seed mass and germination ability (determination index R2=0.93) and seed mass and germination speed (determination index R2=0.82). Obtained results indicated that important seed quality improvement can be achieved after removal of 15-20% of smallest seeds from the seed lot.