Different culture media have a variety of materials that impact a plant’s root system architecture (RSA) and root system quality. 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 the 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 a 30:70 of 5-peat moss- palm peat, 6- cocopeat -palm peat, 7- perlite -palm peat and 8- vermicompost-palm peat under greenhouse conditions and RSA of the seedlings were evaluated by GiA-Roots software via their images, at four-leaf 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) observed in seedlings grown on perlite-vermicompost-coco peat (control) which lacked palm peat, as well as the minimum network volume, number of connected components, and network depth were observed in control. While, 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) observed in seedlings grown under peat moss-vermicompost-palm peat (30:10:60). As a result, a culture medium containing 30% peat moss, 60% palm peat and 10% vermicompost improved RSA in cucumber seedlings and palm peat was recommended as a sustainable component of the culture medium in cucumber seedlings as a natural and local biological resource.