Vertical greenery system (VGS) is a subset of urban green infrastructure that ameliorates thermal performance, potential energy savings, and urban heat island. Plants provide shadow effects through the absorption or filtration of the heat radiant, which respond to these issues. The frequent variable used to indicate the leaf mass of a plant is the leaf area index (LAI). There are two methods to measure LAI: direct and indirect methods. However, little attention was given to calculating the LAI using direct measurement in VGS. This study was undertaken to distinguish the LAI value from four plant species, i.e., Philodendron burle-marxii, Phyllanthus cochinchinensis, Nephrolepis exaltata, and Cordyline fructicosa ‘Miniature’ in the industrial city of Pasir Gudang. An image analysis tool was used to facilitate the measurement. The results showed the LAI values are highly dependent on the number of leaves. It also found plants that keep growing have the highest LAI value. Importantly, the characteristics of a plant need to be considered before planting in a shrub bed.