Magnetic field may be applied as a physical factor to improve germination capacity as well as growth and development of plants. In order to investigate the influence of stimulation with magnetic field and fertilization on the yield and quality of sugar beet roots, a field experiment was carried out in 2015 and it was designed to examine three cultivars of sugar beets, two variants of magnetic stimulation applied to seeds: stimulation in the magnetic field of 40 mT, and control conditions (no stimulation), as well as two variants of mineral fertilization: optimal, based on the contents of nutrients in soil, and control conditions (no fertilization). Observation of the plants’ growth and development was conducted during the vegetation period. The examined values included yield of roots and leaves, as well as contents of heavy metals, macro- and micro-elements and sugar. The observations carried out during the experiment and following harvest showed that the applied variable factors used in the experiment, i.e. the pre-sowing stimulation with magnetic field as well as properly designed fertilization, positively affect the parameters of the plants germination, growth and development as well as the contents of sugar in the examined sugar beet roots.