This study, and similar studies performed on other vegetable test crops, is aimed at the production of high quality substrate for vegetable production. The base for the preparation of these substrates is Pester peat, which is, by the rank of its physical-chemical qualities, classified in the highest quality group in the world. In addition to peat, for the experimental production of substrates, altogethert forty-five, we applied sheep manure, CaC03, zeolite and a complex mineral fertilizer 15:15:15, in various combinations and quantities. To be able to determine whether the degree of peat mineralization affects the quality of pepper seedling production, we produced the substrates in which the peat component is composed only of mineralised peat, semi-mineralized and non-mineralized peat. Based on the test results, it was concluded that the substrate quality was not affected by the ratio of the mineral and organic peat in it, but the quantity of the added sheep manure and mineral fertilizers. The effect of added quantities of ground limestone and zeolite did not affect the habit of pepper seedlings, which does not mean that the higher quantities of these materials would not have a positive effect. We shall test it in our future experiment.