A field experiment was set up at the Experimental Farm of the El-Quassassin Horticultural Research Station, Hort. Res. Inst., ARC., Ismailia Governorate, Egypt, during two winter seasons (2022/2023 and 2023/2024), with the aim to achieve the optimal growth and flowering productivity of marigold (Calendula officinalis L.). Three planting dates (September 15^th, October 1^st and October 15^th) of 2022 and 2023, four combination treatments between nitrogen fertilizer and algae extract (algae extract (AE) at 3 ml/l, nitrogen at 100% of the recommended rate (RR), 50% RR of nitrogen + AE at 3 ml/l and 75% RR of nitrogen + AE at 3 ml/l) and their interaction treatments were tested. The obtained results indicated that the early sowing from  September 15^th followed by October 1^st increased plant height, branches number per plant, fresh and dry weights of herb per plant, number of flowers per plant and flower diameter as well as chlorophyll a and b contents, phosphorus, potassium percentages and flowers fresh and dry weights per plant per season compared to the third planting date under sandy soil conditions. Applying nitrogen fertilization at 100% RR followed by 75% RR + AE at 3 ml/l treatments gave the highest values of abovementioned parameters. In general, planting pot marigold seedlings on September 15^th followed by October 1^st as well as fertilization with 100% RR of nitrogen or 75% RR of nitrogen + spraying with 3 ml/l of algae extract five times per season manifests to enhance growth, flower yield and chemical constituents of Calendula officinalis under Ismailia Governorate conditions. Also, the highest fresh and dry yield/fed/season were obtained from the combined treatment of growing date on October 1^st as well as nitrogen fertilization at 100% RR followed by 75% RR + algae extract at 3ml/l, during the two seasons.