Baltic seaweeds (Enteromorpha sp.) were extd. with aq. soln. of KOH (1 M) at room temp. for 30 min. The exts. were dild, down to concn. 2.5-10% and used for cultivation of Lepidium sativum. Natural biomass of algae, algal exts. and the germinated plants was studied for elemental compn. Addnl., the av. length of the plants was measured and compared with that from the control group (distd. water). Lepidium sativum in the exp. group (seaweed ext. 2.5%) was by 15% longer than in the control group. The content of microelements (B, Cu, Fe, Mn, Zn) was also higher in all exptl. groups than in the control group.