Supercrit. exts. from Spirulina sp. microalgae and baltic seaweeds as well as protein hydrolyzates of keratin were used as biostimulators of the cress (Lepidum savitum) growth. Algal extract - contg. formulations were superior to control samples (11-80% fresh sprout mass increase) and similarly effective to com. prepn., however in 3-times higher concn. The keratin hydrolyzates were less efficient than the algae derived ones.