Buckwheat is an economically important gluten free cereal, and it is a good source of protein, fiber, and energy. The field experiments with buckwheat variety “Novosadska” were set in two experimental years in Pancevo, Serbia. The aim of this study was to determine the most optimal technology for buckwheat production. The study aims were to investigate the effects of (1) row spacing: RS1-25 cm and RS2-50 cm; (2) nutrition variants: (N1) 0 kg ha−1 NPK; (N2) NPK 30 kg ha−1; (N3) NPK 60 kg ha−1; and (N4) NPK 90 kg ha−1; (3) environment: Y1-2018 and Y2-2019; and their interactions on the plant height (PH), number of lateral branches (NoLB), mass of seeds per plant (MSP), number of seeds per plant (NoSP), buckwheat grain yield (GY); and (4) the correlations among these traits. All tested parameters of buckwheat significantly varied across row spacing, environment, and nutrition. The average grain yield in the row spacing, RD1-25 cm, was significantly higher than in the wider spacing, RD2-50 cm, and in 2018 than 2019 as well as with the nutrition NPK applied in the amount of 90 kg ha−1 in relation with all the other nutrition variants. All the studied agronomic traits were positively and strongly correlated with GY.