The current investigations on green onion (Allium cepa L.) commenced during the crop season of 2021–2022 at the University of Mosul, Mosul, Iraq. The presented research examined the effect of foliar application of humic acid and seaweed extract on the growth and production of green onions. The first factor involved spraying of humic acid (H) at different concentrations (0, 1, and 2 ml L^-1). The second factor had the foliar application of seaweed extract (Super 50) (S) with different concentrations (0, 1, and 2 ml L^-1). The study used the local onion cultivar Crystal in the research, planted in a randomized complete block design with three replications. Furthermore, spraying with seaweed extract, and humic acid not only exceeded the control treatment in tubular leaf count, bulb width, and bulb length, but also surpassed the vegetative growth and growth rate in onions. The best measurements came from the foliar treatment, where the interaction of humic acid with seaweed with the same concentration (2 ml L^-1) resulted in no significant differences for growth traits and bulb yield. However, the bulb yield was 693.3 t ha^-1 in the experimental treatments, while 553.3 t ha^-1 for the control group.

Keywords: Green onion (Allium cepa L.), humic acid, seaweed, factors interaction, growth, bulb yield traits

Key findings: Modern fertilization methods, including using organic fertilizers and seaweed, resulted in enhanced vegetative growth attributes and increased yield of green onions (Allium cepa L.).