The majority of gladiolus cultivars are sensitive to spike bending and postharvest longevity. The field trial was performed to evaluate the use of various calcium fertilizers on some biochemical attributes, growth and postharvest trading criteria of Gladiolus grandiflorum L. cv ‘Rose supreme’. During two consecutive years, two Ca sources at different levels (0, 0.3, 0.6, 0.9, 1.2 and 1.5 g L-1) were sprayed on the gladiolus plants when the tip of flowering stem was observed and 10 days after the appearance. The results in both years revealed that, in comparison to non-Ca sprayed plants, total soluble carbohydrates and total protein content were increased by ~74.2% and 217% in the plants at 1.5 g L-1 Ca applied, whereas the highest total anthocyanin and proline content were observed at 1.2 g L-1 Ca application. The membrane stability augmented as the Ca fertilizer level increased. Antioxidant enzymes, namely POD and SOD in petals remained at the highest with 1.2 g L-1 Ca. Ca applied at 1.2 g L-1 imparted greater useful influence on spike strength and vase life longevity (by ~21.5 days) than the other concentrations. Ca (NO3 )2 fertilizer increased flower longevity by 11/7% longer than did . However, corm features have not been significantly affected by any Ca sources and levels. Among various biochemicals and floral features, antioxidative enzymes were revealed to have a positive correlation with vase life. Path analysis revealed that only total protein and Ca content recorded the highest magnitude (3.417 and 1.363, respectively) of positive direct effect on vase life. Proline content and number of florets per spike had strong negative direct effects of -3.068 and -2.580, respectively, on vase life. Our results suggest that Ca prolongs the vase life through improving antioxidative defense system and some osmolytes.