The present study was aimed to determine the effect of V2, VR10 and VR1 experimental biostimulants application on yield related main traits (plant height and stems number per m2) and on forage productivity of Prista 4 alfalfa variety. The study was carried out in experimental field at Institute of Agriculture and Seed Science "Obraztsov chiflik" - Ruse, from 2019 to 2021. The biostimulants were foliarly applied two times in each regrowth. There was found positive effect of the biostimulants application on the growth and development of alfalfa. The additional introducing of VR10 and VR1 biostimulants contributed to higher alfalfa grass stands by 17.13 and 14.36%, respectively compared to control. Foliar spraying with V2 biostimulant had more clear pronounced positive effect on the stem development. According to the three-year results the average stems number per m2 at V2 treatment significant exceeded the control by 4.78%. V2 biostimulant distinguished with a stronger positive effect on the forage productivity among studied products. Its application resulted in significant increases on green mass and dry matter yields by 4.18 and 4.99%, respectively over the control. V2 application gives promising results and reason to be recommended as a corrective component in technology of growing alfalfa for forage.