A current experiment was carried out at a private farm under sandy soil conditions in El-Bostan area, El-Behera Governorate, Egypt over two consecutive seasons of 2019/2020 and 2020/2021. The aim was to investigate the effect of some plant growth bio-stimulants on cassava plants (Indonesian cultivar) growth and yield as well as the roots storability. The experiment contained thirteen treatments: potassium humate (1, 2, and 4 g/l), fulvic acid (1, 2, and 4 g/l), chitosan (1, 2, and 4 g/l), and seaweed extract (1, 2, and 4 g/l), in addition to a control treatment. Cassava plants were sprayed four times with the experimental treatments at 60, 90, 120, and 150 days after planting date. The experiment was set up with three replicates in a completely randomized block design. The obtained results showed that foliar spraying with seaweed extracts, fulvic acid, or chitosan at rates of 2 or 4 g/l resulted in the highest values for plant height, the number of main stems, number and weight of roots/plant, root length, and root diameter. Furthermore, cassava plants sprayed with seaweed extracts, fulvic acid and potassium humate at a rate of 2 g/l, had the highest levels of starch content in the roots, while treatment with seaweed extract at a rate of 4 g/l recorded the highest levels of N, P, and K in the shoots. The recommendations are that foliar spraying with seaweed extract at a rate of 4 g/l could be used to increase the production and quality of cassava roots, as well as the content of mineral elements in the shoots and the starch content in the roots. In addition, a storage period of 40 days at a temperature of 5 °C could be attained by using chitosan at a rate of 1 g/l or seaweed extract at 4 g/l as a field treatment.