The aim of this work was to study the bark of aspen growing in the suburban area of Krasnoyarsk and obtain water-ethanol extracts based on it, with different growth-regulating activity. The paper deals with the possible processing of aspen bark with the release of biologically active substances of the phenolic group. Water-ethanol solutions of aspen bark of different concentrations were used as an extractant. The regression equations and the optimum conditions of extraction of the bark of aspen with the allocation of the maximum amount of extractives. Studies have shown that aspen bark contains a variety of groups of biologically active substances, including phenolic group: tannins (tannins from 17.0 to 18.0%) polyphenols (glycosides – 0.71–0.84%), flavonoids – 0.33–0.43%; pigments: (chlorophylls from 0.63 to 0.74%; carotenoids (from 0.52 to 0.55%). The obtained mathematical models were adequate to the studied processes at 95% confidence probability. The optimal values for maximum extraction of extractive substances: the concentration of ethanol was 65%; the duration of the process – 3.5 hours, hydro – 15. In the optimal mode was obtained aspen bark extract, its characteristics coincide with the requirements of TU 9377-162-20680882-10 "raw Materials for the production of biologically active additives "aspen bark Extract "thick". It was established that water-ethanol extracts of aspen bark have depending on the concentration of growth-inhibiting or stimulating activity. In the range of concentrations from 0.1 to 10 g/l, they have an inhibitory effect, with further dilution from 1∙10-2 to 1∙10-4 g/l, a stimulating effect is observed. The tendency of increasing the growth of seedlings of cereals, %: corn – 30, barley – 40 and wheat – 35; legumes, %: peas – 35, beans – 45 and lentils – 25 compared with the control at a concentration of extractive substances of aspen bark 1∙10-3 g/l. the Data obtained may be useful after appropriate sanitary-toxicological studies to increase the germination and germination of seeds of legumes and cereals.