Geese are the dominant species among waterbirds overwintering along the middle and lower Yangtze River who prefer Carex spp as their main food source. As the largest freshwater lakes connected to the Yangtze River, the consequent growth of the wetland vegetation at Poyang Lake is greatly affected by hydrological factors which may determine the exposure time of the meadow and as well as the effective growth time of wetland vegetation. However, geese are of highly selectivity of food, Carex spp is just suitable during a specific growing period and plant height is one of the important selection factors. Clarifying the relationship between feeding characteristics of geese and the growth process of Carex spp is therefore significant to determine the spatial-temporal pattern of suitable habitats for geese conservation. Taking Changhuchi Lake, a typical sub-lake of Poyang Lake National Nature Reserve, as the study area, this study undertook in-situ experiments as well as lab analysis of Carex spp during the spring growth season (from early March to early May), including 12 field surveys of plant height and 7 field surveys of aboveground biomass along four elevation gradients. Data extracted from remote sensing interpretation, meteorological data and field survey data were combined to identify the flood recession dates as well as the effective growth time of different elevation gradients. By incorporating Logistic equation and the feeding characteristics of geese, the time window fit for geese's feeding on vegetation was reversely deduced from growth curve model. The results showed that there was a significant positive correlation between plant height and aboveground biomass and both of them fit the Logistic growth model; hydrological regime and temperature jointly affected the growing process of Carex spp. Delayed flood recession will influence the vegetation pattern for geese to feed on due to the low temperature limit. When the exposure time of Carex spp reached 12-28 days in autumn and 83-182 days in spring, they provided an appropriate time window for geese to feed. Our study proposed a method to determine the time window of Carex spp fit for overwintering geese and analyzed the influencing mechanism for hydrological factors on wintering geese's food availability. It was evidenced that a 20-day delay of flood recession would cause a great mismatching between the growth patterns of Carex spp and the foraging requirements of wintering geese in their peak period through our field monitoring. This study is of great contribution to the hydrological regulation and management of Poyang Lake wetland.