This paper presents preliminary results on employing Terahertz (THz) technology for measuring the water contents of leaves. The main purpose of this work is to highlight transmission constraints of terahertz radiation through the plants in the THz frequency region. Multiple leaves of plants are examined using the THz Swissto12 system, and the effect of thickness and water contents on transmission loss and attenuation are observed at different frequency regions, which can lead to meaningful information to study and analyse the existence of any pesticides in leaves with terahertz frequencies. The results of this paper pave the way for applicability of terahertz frequencies for sensing the quality of life in plants.