Different culture media have various materials that impact root system architecture (RSA) and root system quality in plants. Finding the most compatible RSA of cucumber seedlings among the eight mixed culture media is critical to plant productivity. In this experiment, cucumber seeds were sown in eight mixed culture media, including a volume ratio of 30:10:60 of 1- perlite-vermicompost-coco peat as the control group, 2- peat moss-vermicompost-palm peat, 3- cocopeat vermicompost-palm peat, 4- perlite-vermicompost-palm peat, and 30:70 ratios of 5- peat moss- palm peat, 6- cocopeat -palm peat, 7- perlite -palm peat and 8- vermicompost-palm peat under greenhouse conditions. RSA of the seedlings was evaluated by GiA-Roots software via imaging at the fourleaf stage. The results showed that the minimum network length, network area, and network perimeter (821.6 cm, 7598.3 cm2, and 2102.3 cm, respectively) in the seedlings occurred on perlite-vermicompost-coco peat (control) which lacked palm peat. The minimum network volume, number of connected components, and network depth were observed in the control. However, the maximum network length, network volume, number of connected components, network width, network area, and network perimeter (88862.8 cm, 2076390.9 cm3, 23.2, 4567.4 cm, 332356.1 cm2, and 132068.9 cm, respectively) occurred in seedlings on peat moss-vermicompost-palm peat (30:10:60). Thus, a culture medium containing 30% peat moss, 60% palm peat, and 10% vermicompost improved RSA in cucumber seedlings. Palm peat was recommended as a sustainable resource to comprise culture media for cucumber seedlings.