In the years 2002-2004 the experiments concerning potato growing in organic system on 2 types of soil were carried out. The main aim of these eperiments was an assessement of 2 ways preparation of seed potato tubers (presprouted and without) on some physiological phases, plant development and potato tuber yield. Positive effect of presprouting on emergence, blooming and maturity of potato plants was confirmed. There was also positive influence on plant development and LAI index but only on heavier soil. The yield from presprouted mother tubers was higher but there was no signifficant differences. The reason was probably Alternaria solani, a patogen which attacks first older plants - in this case those origined from presprouted seed potato tubers. Positive effect of presprouting was smaller than negative effect of disease.