In order to evaluate the growth and quality of head lettuce cv. Big bin (Capuchi) in response to salicylic acid at different rates and dates of application as foliar spray, a field experiment was done during seasons of 2022 and 2023. The current study established at the Experimental farm, Faculty of Agriculture, Mansoura University, Dakahlia Governorate, Egypt. Four rates of salicylic acid (0.0, 0.1, 0.2 and 0.3 g/l) at different dates of application (30, 40 and 50 days) and their combinations were applied to enhance lettuce growth and productivity. The obtained results pointed out that sprayed lettuce plants with salicylic acid at 0.2 g/l significantly enhanced growth traits such as, plant height, fresh weight of foliage and leaves per plant. As well as, leaves numbers and area per plant, chlorophyll content and NPK percentages in outer leaves, head yield and its physical and chemical quality compared to the other concentrations under study. The highest values in these growth traits, leaves chemical constituents and heads yield and their quality was achieved when lettuce plants sprayed at early date (at 30 days after transplanting) compared to mid and late dates of season growth. In general, sprayed lettuce plants at early date 30 days from planting with salicylic acid 0.2 g/l significantly improved head lettuce cv. Big bin growth, yield and quality compared to the other combination treatments under Dakahlia Governorate conditions.