Mustard greens are vegetables that are popular with people because they provide various benefits. Increasing mustard greens production can be done by providing adequate nutrition through the fertilization process. Azolla is an aquatic plant that can be used as organic fertilizer. The aim of this research is to provide information regarding the use of Azolla as a liquid organic fertilizer and recommendations for the best dosage to increase the growth and yield of mustard greens. The Greenhouse of the Department of Agroecotechnology, Faculty of Agriculture, ULM Banjarbaru, will be the research location from September to October 2023. Completely Randomized Design (CRD) with a single factor is the research methodology used in this research. The treatments tested were P0 = control or without POC Azolla, P1 = POC Azolla 10 mL L-1, P2 = POC Azolla 20 mL L-1, P3 = POC Azolla 30 mL L-1. The treatment was repeated five times and then there were twenty experimental units. The results of research on the parameters of plant height, number of leaves, leaf width, leaf length and plant weight show that the application of Azolla liquid organic fertilizer has an effect on the growth and yield of mustard greens (Brassica juncea L.). The best treatment is P3 treatment with a dose of Azolla POC solution of 30 ml L-1.