Organic fertilizers mitigate the impact of salinity on plant growth by enhancing nutrient uptake. This study investigated the effects of organic fertilizer on greenhouse cucumber growth under irrigation water salinity. We examined the impact of four salinity levels of irrigation water (0.4, 3, 6, and 9 dS/m) and five fertilizer treatments including no fertilizer, Zargreen fertigation at concentrations of 2, 4, and 6 ml/L, and foliar fertilizer at a concentration of 4 ml/L. The experiment was conducted as a factorial in a completely randomized design with three replications. The results demonstrated that the lowest plant growth occurred at 6 and 9 dS/m salinity levels. At a salinity level of 9 dS/m, applying 4 ml/L and 6 ml/L of fertigation increased stem length by 22% and 12.8%, respectively, while plant dry weight increased by 46.5% and 32.5%. Additionally, root dry weight increased by 34.7% and 30%, respectively. The use of 4 ml/L and 6 ml/L of fertigation also enhanced chlorophyll a level by 54.9% and 69% and carotenoid content by 36.4% and 41.7%. Moreover, there were reductions in proline levels by 20.8% and 20.4%, and total antioxidant capacity decreased by 21.5% and 25.2% at a salinity level of 9 dS/m. Based on the results of organic fertilizer effectively mitigated the negative impacts of salinity on growth, leading to improved plant development compared to the control group.