In order to investigate the interaction effects of humic acid and nano-calcium chelate on Gerbera jamesonii cv. Dune, an experiment was performed as factorial based on a completely randomized design with two factors and three replications in hydroponic conditions. First factor was included: humic acid in 4 concentrations of 0 (control), 500, 1000, and 2000 mg L^-1 as drench and the second factor: nano-calcium chelate at 4 concentrations of 0 (control), 1, 2, and 3 g L^-1 as foliar application. Indices such as number of leaves and leaf area, fresh and dry weight of inflorescence, vase life, time of bud to floral anthesis, flower longevity, and antioxidant enzymes activity were measured. Results showed that humic acid and nano-calcium chelate in comparison with the control increased the activity of antioxidant enzymes such as catalase, ascorbate peroxidase, and guayacol peroxidase about 7, 6, and 7 times, respectively. Vase life and flower longevity were affected by application of humic acid and nano-calcium chelate compared to the control as showed a 57 and 31% increasing, respectively. Flower diameter and flower stem diameter showed 20% increasing compared to control. With increasing the concentration of nano-calcium chelate, leaf area increased. The number of leaf was increased only with increasing the concentration of humic acid. Generally, application of both humic acid and nano-calcium chelate was effective on improving some characteristics of gerbera and approximately 2000 mg L^-1 humic acid and 2 g L^-1 nano-calcium chelate were more effective.