Background <p>Sex expression in plants is a complex process influenced by genetic, environmental, and hormonal factors. In cucumbers, a high male-to-female flower ratio significantly contributes to low yields. The application of exogenous plant growth regulators can modify the sex ratio and flowering sequence, potentially improving productivity. In this experiment, effects of plant growth regulators, Spermidine (Spd) at concentrations of 0.25, 0.5, and 0.75&#xa0;mmol/L and methyl jasmonate (Mj) at concentrations of 0.1, 0.25, and 0.5&#xa0;mmol&#xa0;L^− 1 on sex expression, chlorophyll content, antioxidant capacity, and fruit quality and yield of cucumber plants evaluated.</p> Results <p> Results indicate that, overall, female flowers, the female-to-male flower ratio, chlorophyll b, yield, and antioxidant capacity increased in autumn compared to spring. Among various growth-regulating treatments, the application of 0.75&#xa0;mmol&#xa0;L^− 1 Spd resulted in a 246% increase in the female-to-male flower ratio and a 125% increase in yield compared to the control in autumn. In contrast, the highest number of male flowers was observed in spring under the control treatment, leading to reduced yield during that season.</p> Conclusion <p>Overall, Spd at 0.75&#xa0;mmol&#xa0;L^− 1 had a more significant impact on improving most traits examined in both spring and autumn compared to other growth-regulating treatments. However, methyl jasmonate was less effective, particularly at lower dosages.</p>