The objective of this study was to evaluate the effects of the Ca:Mg ratio, magnetic field (MF), and mycorrhizal amendment on the yield and mineral composition of rose geranium. The experiment was structured as a 3 × 2 factorial experimental design, with three levels of the Ca:Mg ratio (2.40:6.78, 4.31:4.39, and 6.78:2.40 meq·L−1), 6.78 Ca:2.40 Mg meq·L−1 denoted by “High-Ca:Low-Mg,” equal proportion of Ca and Mg (4.31 Ca:4.39 Mg meq·L−1) represented by “EP-Ca:Mg,” and 2.32 Ca:6.38 Mg meq·L−1 denoted by “Low-Ca:High-Mg,” two levels of MF (no MF, denoted by “0 MF,” and 110 mT, denoted by “1 MF”) and split treatments of mycorrhizae (zero mycorrhizae denoted by “0 Myco,” and 20 mL mycorrhizae denoted by “1 Myco”) were used in this study. The results show that the plant height and branch dry mass were significantly (P < 0.05) affected by the Ca:Mg ratio. No significant effect of Ca:Mg ratio, MF, or mycorrhizae on the number of leaves, foliar mass, leaf dry mass, or yield was detected. Phosphorus, K, S, Fe, and B accumulation in the stem were unaffected, as were leaf N, P, K, Ca, S, Fe, B, and Cu. However, some agronomic attributes (plant height, number of branches, root length, and chlorophyll content) and mineral composition (Stem-N) were optimized when the 1 MF exposed nutrient solution was used with about equal proportions of Ca and Mg. This Ca:Mg ratio in the nutrient solution, together with the exposure of rose geranium plants to 1 MF, yielded positive results. The findings of this study can be applied to improve the production of rose geranium by enhancing the growth and mineral concentration of this crop.