Two field experiments were carried out during the two successive summer seasons of 2019 and 2020 at a private farm located in Mit Taher village, Minyet El-Naser city, Dakahlia Governorate, Egypt to evaluate the effects of sowing dates, some foliar substances (trehalose at 25 and 50 ppm and nitric oxide at 30 and 60 ppm) and their interactions on vegetative growth, chemical constituents of leaves, setting percentage as well as seed yield and quality of common bean plants cv. Nebrasca. The obtained results indicated that most studied parameters differed significantly due to different sowing dates and applied foliar substances in both growing seasons. Sowing in early date (March 1^st) recorded the highest values of all studied characteristics except for prolin content in plant leaves. Also, foliar application with either nitric oxide or trehalose proved superiority as compared with the control in most studied parameters. Plants in the absence of foliar applications recorded the highest values of prolin content in plant leaves. Plants sown in the early date (March 1^st) and sprayed with nitric oxide at 60 ppm recorded the best values of vegetative growth, chemical composition, setting percentage, seed yield and germination in both growing seasons. Thus, this treatment could be recommended to improve common bean plants performance under similar conditions of this study. Additionally, foliar application with nitric oxide at 60 ppm in the intermediate sowing date recorded higher yield nearly equal the control treatment in the early sowing date in both seasons.