Ecological fruit production in Poland is limited by, among other things, a shortage of biological preparations for the protection of fruit trees and shrubs from diseases and pests as well as a lack of bio-fertilizers needed to supplement periodic nutrient deficiencies, especially of nitrogen. In the present study, the effectiveness of several bio-fertilizers was assessed under the conditions of an organic sour cherry orchard. The products taking part in the assessment included: ‘Fertigo’ ecological manure, Micosat F12 WP, Micosat F MS 200, Humus UP, Humus Active, Aktywit PM, BF Quality, BF Amin, Tytanit, and Vinassa. The influence of the applied fertilizers on the growth of sour cherry trees of the cultivar ‘Debreceni Bötermö’, their fruiting and the quality of the harvested fruit was assessed. The experiment was conducted within the Eko- TechProdukt Project being implemented in 2009-2014 at the Research Institute of Horticulture in Skierniewice. The experimental trees, grafted on mahaleb cherry seedlings, were planted in the spring of 2009 at a spacing 4.0 x 2.5 m, and were fertilized every year with the fertilizers listed above. The study has shown a beneficial effect of the preparation Vinassa on the growth and fruiting of sour cherry trees.