The use of buckwheat as a source of rutin for medicine or food supplement requires a high content of this component in pimary row materials. The study was aimed at the investigation of the influence of stand density and sowing dates on the rutin content in the aboveground parts at the stage of flowering and achenes of two buckwheat species (Fagopyrum esculentum and Fagopyrum tataricum). The rutin content in the aboveground parts of buckwheat was significantly higher in plants sown in mid-May. The sowing date did not influence the rutin content in the achenes. The whole buckwheat plant contained the highest content of rutin in 25 cm rows with a sowing ratio of 200 achenes per square metre. However, the final rutin amount obtained from a buckwheat stand depended on the production of biomass. Common buckwheat provided a higher rutin yield because it produced a higher amount of biomass of inflorescences, the part rich in this flavonoid. Therefore 12.5 cm rows with 400 seeds per square metre are suitable for rutin production because of the higher number of plants. We can recommend tartary buckwheat for achene production as a source of rutin for human nutrition or food supplement because it provides twenty-fivefold more rutin than common buckwheat.