Two field experiments were carried out at experimental farm of Faculty of Agriculture, Zagazig University, Egypt, during the two summer consecutive seasons of 2018 and 2019. To study the impact of sowing dates and some amino acids on the roselle (Hibiscus sabdariffa L.) yield in terms of number of fruits per plant, dry sepal’s yield per plant and per feddan as well as its chemical constituents in terms of total chlorophyll (SPAD) and anthocyanin (mg/100g as dry weight) contents. A split-plot experiment was carried out in the field based on a randomized complete block design with three replications. The main plot was four sowing dates (15th April, 1st May, 15th May and 1st June) and the sub-plot was five amino acids treatments (tap water as control, tyrosine and glutamine acids each at 100 or 200 ppm concentrations). The results showed that the early in sowing from June1 to April 15 increased fruit number per plant, dry sepals yield per plant (g) and per feddan (kg) as well as total chlorophyll content and anthocyanin content. Also, all the values of the studied parameters were significantly increased when the roselle plants sprayed with glutamine acid at 200 ppm compared to control. In final, planting roselle seeds in 15th April and sprayed with 200 ppm glutamine four times per season manifests to enhance yield and is adequate for fulfilling the highest anthocyanin contents in sepals of roselle under Sharkia Governorate conditions.