This study examined optimized water management strategies for fresh cut flowers grown in plastic greenhouses in the Dianchi Basin. During the study period (April 2022 to February 2023), fresh cut flowers in plastic greenhouses in the Dianchi Basin were selected for the study, and a drip irrigation system was deployed in the cut-flower greenhouse sample plots, soil temperature and moisture at different depths were continuously monitored using soil sensors, and evapotranspiration under the greenhouse environment was estimated using the water-balance method and the Penman-Taylor equation. The results showed that soil temperature and moisture varied most significantly in the surface layer (0–10 cm), while it was relatively stable in the deeper layer (50–80 cm); moreover, soil moisture gradually increased and stabilized with increasing soil depth. The actual evapotranspiration (ETc) was significantly higher than the reference evapotranspiration (ET0) during the study period. This study aims to promote the comprehensive and rational utilization of water resources in the Dianchi Basin, to provide scientific and theoretical basis for the sustainable development of agriculture in the region, and to continuously promote the development of water-saving agriculture.