The aim of the conducted observations was to examine the effect of fertiliser produced based on plant digestate and resulting from the process of anaerobic fermentation of a substrate with sorghum (20%), beet (60%), rye (10%) and grass (10%) on the growth and yield of sorghum and corn. A strict, single-factor pot experiment was carried out in 2017–2018 in the Swojec Agricultural Experimental Unit at the University of Life Sciences in Wrocław. Fertilisation with digestate was the tested factor, with a focus on its influence on selected energy plants. Sucrosorgo sorghum and Atletico maize were analysed. During the research, the pots were placed in a vegetation hall. The research proved that the use of digestate-based fertiliser improves the productivity of both sorghum and maize, but only with an additional dose of basic macronutrients. The optimal variant is a fertiliser dose of 20 g enriched with 1.0 NPK. Increasing the dose to 30 g and 1.5 NPK generally did not result in a significant increase in plant height or in fresh and dry weights.