This study aimed to : (1) to determine the interaction between AB mix concentration and spacing on the growth of bokchoy in the floating raft hydroponics, (2) to determine the AB mix concentration and spacing that gave the best growth for bokchoy on the floating raft hydroponic. Experiments were carried out using a split plot design with AB mix concentration as the main plot consisting of three levels, namely K1 (10 ml l-1 ), K2 (12 ml l1 ), and K3 (14 ml l-1 ) and spacing as subplots consisting of three levels, namely J1 (10 cm x 10 cm), J2 (10 cm x 15 cm), and J3 (10 cm x 20 cm). From these two factors, nine treatment units were obtained, each treatment unit was repeated three times in order to obtain 27 experimental units. The results showed that: (1) there was a significant interaction between AB mix concentration and spacing to root volume of 14 DAP (Day After Planting), and leaf area index at 21 and 28 DAP, (2) AB mix concentration treatment of 14 ml l -1 gave the highest average leaf area index with a value of 2.559.

Keywords : Floating Hydrophonic, Growth, Treatment.