The growing world population is putting pressure on food and feed production. For many years, selenium deficiencies have been observed in the diets of the inhabitants of most European and other continental countries, both in the environment and in food and fodder. Therefore, it is becoming necessary to supplement these deficiencies. A 3-year field study was therefore carried out to determine the effect of sulphur (0, 15 and 30 kg S ha−1) and selenium (0, 10 and 20 g Se ha−1) on the yield and biometric traits of winter forms of spelt wheat and common wheat, as well as the timing of application (at the tillering stage, BBCH 22–24, and the stem-shooting stage, BBCH 31–34). Sulphur fertilisation had a slight but positive effect on both the grain and straw yields of both wheat species, especially spelt wheat. The highest increase in spelt wheat grain and straw yield and common wheat straw yield was obtained after applying sulphur at a dose of 15 kg S ha−1, by 3%, 5% and 5%, respectively. In the case of selenium, a higher dose (20 g Se ha−1) had the most beneficial effect on the grain yield of spelt wheat (5% increase) and common wheat (8% increase). In turn, a lower dose of this element (10 g Se ha−1) contributed to an increase in the straw yield of both wheat species, by 10% and 17%, respectively. The yield of spelt and common wheat was not dependent on the timing of Se application. The beneficial effect of S and Se fertilisation on the growth and development of the tested plants is also indicated by the high (exceeding 1) tolerance index for Se and the yield response for S. The effect of S and Se on the weight of a thousand grains was not clear-cut. The density of spelt and common wheat ears increased as a result of the impact of S and Se (S: by 6% and 5%; Se: by 10% and 15%, respectively). Delaying the application of Se contributed to an increase in the density of the tested plants.