Iron (Fe) deficiency is frequently encountered on calcareous soils and is usually overcome by application of Fe fertilisers. In the present study, maize plants (Zea mays L. cv. Merit) grown in calcareous soil were foliar-sprayed with or without 100 µg Fe g^–1 in the forms of Fe₃O₄ nanoparticles (NPs) and ethylene diamine-N,N-bis(2-hydroxyphenylacetic acid) Fe sodium complex (Fe-EDDHA), at different growth stages. Uptake and translocation of Fe within the plant were monitored by atomic absorption spectroscopy, vibrating sample magnetometer, dynamic light scattering and transmission electron microscopy, and physiological parameters were evaluated. Iron treatments improved maize photosynthesis and hydrogen peroxide and superoxide anion scavenging capacity and lowered the rate of membrane lipid peroxidation. Iron treatment also accelerated vegetative growth and caused earlier entrance to the generative phase. Differences between ameliorative effects of Fe-EDDHA and Fe₃O₄ NPs were particularly noticeable in the generative growth phase. Improvement of calcium, Fe² , total Fe, and ferritin contents were more pronounced in Fe₃O₄ NPs treatments (164%, 200%, 300%, and 200% of the control, respectively). Improved growth of maize treated with Fe₃O₄ NPs can be attributed, at least in part, to the increase in ferritin and its critical role in maintenance of Fe homeostasis and balance of the plant redox system.