Current climate models predict more intense rainstorms and temperature extreme events under future global climate change. Estimation of environmental factors thresholds might provide important information for the common patterns of species distributions and management of wetland ecosystems. The laboratory experiment and the greenhouse experiment examined separately the effects of temperature (10 constant temperature regimes of 8, 10, 12, 14, 16, 19, 22, 26, 30 and 35 degrees C) and flooding depth (10 flooding depth treatments of -15, -10, -5, 0, +5, +10, +15, +20, +25 and +30 cm relative to the substrate surface) on rhizome bud sprouting and establishment of Phragmites australis. Our results revealed that the final sprouting percentage, relative growth rate and ramet height showed hump-shaped relationships with temperature. Higher temperature led to shorter mean time to sprout, faster sprouting rate and greater ramet survival. The estimated base temperature for rhizome bud sprouting was 5.0 +/- 1.27 degrees C. The optimum temperature for rhizome bud sprouting and early growth might be the range of 23-30 degrees C. The final sprouting percentage, relative growth rate and ramet height showed unimodal patterns with flooding depth. The mean time to sprout was increased with deeper flooding depth, while sprouting rate and ramet survival were decreased. The optimum flooding depth for rhizome bud sprouting and early growth might be the range of -7 to 0 cm. Our results will contribute to a better understanding of the influence of climate change on early plant recruitment processes and distribution of P. australis.