This study was carried out to investigate the impact of foliar application of Ascophyllum nodosum extract (ANE) to improve the quality and performance of Linum grandiflorum plants. During the two succeeding growing seasons of 2021/2022 and 2022/2023, the study was conducted at the Research Nursery of Antoniadis Gardens, Ornamental Plants and Landscape Gardening Res. Dept., Horticulture Res. Inst., ARC, Alexandria, Egypt. Individual L. grandiflorum seedlings were planted in 25 cm-diameter plastic pots. At concentrations of 0, 2, 4, 6, 8 and 10 ml/l, ANE was added as foliar spray. The results demonstrated that the spraying with ANE extract improved the L. grandiflorum plant height (cm), number of branches/plant, branch diameter (cm), shoot dry weight (g), number of flowers/plant, flower diameter (cm), and root length (cm). Furthermore, the data obtained indicated that the application of ANE spray led to the highest levels of carotenoids, anthocyanin, chlorophyll a, and b, as well as carbohydrates in leaves.