Baltic seaweeds were extd. with dild. H2SO4 at 65 degrees C for 1 h and used as plant germination stimulator (Lepidium sativum). The original biomass, exts. and L. sativum plant materials were analyzed for 18 elements. Addn., the ay. length of the plants was detd. as well as the values of the RGB model parameters (R red, G green and B blue). The plants treated with the seaweed ext. were longer by 10% than the control plants (distd. water). The biomass was enriched in K, S and Ca macroelements and B and Mn microelements. Good fertilizer properties of the algal exts. were confirmed.