A field experiment was conducted during the two winter growing seasons of 2019/2020 and 2020/2021 in Sanhour El-Madina village (31°07' N, 30°43' E), Desouk, Kafr El-Sheikh Governorate, Egypt, to investigate the effects of molasses application methods (soil, foliar spraying, and control), Lithovit fertilizer (0, 0.5, and 0.75 g l-1), and plant growth regulators (GA3 gibberellic acid, GA3+CK cytokinin, and control) on seed production of onion (Allium cepa, L.) cultivar Giza Red. Soil application of molasses generally outperformed foliar application and control in earlier flowering, extended bolting period, increased umbel scapes, umbel diameter, seed setting, 1000-seed weight, and seed yield. Foliar application was significantly better than the control in the previous traits. The percentage of seed germination was markedly increased by foliar or soil application of molasses in favour of foliar application compared with control. Lithovit application (0.5 g l-1) improved most parameters, including earlier umbel emergence, extended bolting, increased umbel scapes, seed set, 1000-seed weight, yield, and germination, than control. Foliar spraying with the lithovit 0.75 g l-1 led to intermediate effects between the control and 0.5 g l-1 for the mentioned parameters. Both growth regulators GA3 and GA3+CK accelerated umbel emergence, enhanced umbel characteristics, increased 1000-seed weight, onion seed yield, and improved germination compared to the control, with GA3+CK showing superior effects. Interactions among treatments were significant for several parameters. The combination of soil molasses, 0.5 g/l Lithovit, and GA3+CK yielded the best results for most traits. These findings suggest integrated management practices incorporating molasses, Lithovit fertilizer, and plant growth regulators can enhance onion seed production.