In formation of fruit quality, an application of bio-stimulants that can protect plants against external unfavorable factors and regulate specifically the plant growth, development and metabolism, is prospective, enabling full realization of a varietal potency. In this paper, the data are summarized on studying influence of meteorological conditions of the growing season and the growing factors on the yield and quality of strawberries grown in the southern Russia in 2006-2010. There are reported the results of using GUMI 20K fertilizer and growth regulators Mival-Agro, Stimolante 66f, Alga mix B Mg at the phases of stem extension, early flowering and ripening of berries to control yield formation and chemical composition of strawberries under extreme weather conditions.