The paper describes a technique for automated analysis of the annual graphs of Normalized Difference Water Index, which enables to allocate framing dates of the spring, summer and autumn growing seasons. The approach proposed and used for detection of growing season dates allows to detect beginning and ending dates for summer season (when the surface air temperature is above +10 °C), in addition to the detection of beginning date for spring season and ending date for autumn season (when the temperature is above +5 °C), as it described by some authors. We describe general idea of the analysis of NDWI annual graphs and some collisions in the graph data, which are possible when the graph is derived from the satellite imagery time series.