The spatial variability of plant-water characteristic in the soil is still unclear. This limits the attempt to model the soil-plant-atmosphere system with this factor. Understanding the non-steady water flow along the soil-plant component is essential to understand their spatial variability. An experimental set-up was designed to collect the data needed to develop more realistic and dynamic model, incorporating the dynamic water flow. The set-up was built using a modified capillary irrigation that allows the step change of soil water content. Step change of micro climates and leaf area size were also experimented. The plant water responses were measured from evapotranspiration level, based on water usage, mass change, soil water potential and moisture content. The data have shown the real dynamic nature of the plant relation such as time lag between the water uptake by the soil-root and the water loss by the leaves. It has also shown the water storage capacity of the soil-plant and the charge and discharge of the internal water reservoirs. A dynamic model for the transient flow of water in the soil-plant was developed based on the analogy of resistance-capacitance relations from the modified capillary system.  The fundamental approach to embed spatial variability in plant-water relation has been deduced.