The overall effect of NH4NO3, KNO3, and KH2PO4 on the biosynthesis of rosmarinic acid and cell biomass by Lavandula vera MM cell suspension was studied by the method of the full factor experiment. Polynomial regression models were elaborated to give a quantitative description of the processes of biosynthesis of rosmarinic acid (Y-1) and cell biomass (Y-2) as a result of the variation of the concentration of NH4+, 0.09 g/L less than or equal to X-1 less than or equal to 0.23 g/L; NO3-, 2.44 g/L less than or equal to X-2 less than or equal to 3.02 g/L; and KH2PO4, 0.170 less than or equal to X-3 less than or equal to 0.425 g/L. Optimization procedures according to the modified Simplex method allowed us to establish the optimal conditions for the biosynthesis of rosmarinic acid by Lavandula vera MM: X-1* = 0.09 g/L; X-2* = 3.02 g/L, and X-3* = 0.170 g/L, where Y-1* max = 1786.74 mg/L (27 times higher compared with the cultivation in the standard Linsmayer-Skoog medium). As a result, modified ingredients of the Linsmayer-Skoog nutrient medium were applied for the cultivation of Lavandula vera MM to achieve a maximum yield of rosmarinic acid.