【Objective】 This study aims to examine how different seedling containers affect the growth, blooming, and physiology of purple-leaf Lagerstroemia indica seedlings. The goal is to determine the optimal seedling containers for growing purple-leaf L. indica container seedlings and to lay the groundwork for effective vetch container seedling breeding. 【Methods】 Taking the excellent new variety of Lagerstroemia indica 'Ebony Embers' as the research object, a total of 9 treatments with different types and specifications of seedling containers were designed to determine the effects of different treatments on the growth, flowering, and physiology of container seedlings. 【Results】 (1) Different nursery containers had significant effects on the growth, flowering, and physiology of .purple-leaf L. indica container seedlings. The growth, root system, biomass, flowering period, flower diameter, inflorescence, soluble protein content, soluble sugar content, relative chlorophyll content, net photosynthesis rate, stomatal conductance, transpiration rate, and other indexes of the container seedlings increased with the container specifications, and all of them reached a significant difference. (2) The C3D3 treatment（25 cm diameter, 25 cm high black root control container） exhibited the greatest in-ground growth, total root length, total root surface area, total root volume, number of root tips, above-ground dry weight, below-ground dry weight, total dry weight, and flowering period. These results were significantly greater than the smallest C1D1 treatment（16 cm diameter, 16 cm high black plastic nutritional cups） by 817.12%, 108.12%, 94.60%, 75.66%, 144.14%, 135.67%, 228.45%, 164.65, 20d; additionally, the C1D3 treatment had the highest growth in terms of seedling height, crown growth, leaf area, inflorescence length, and width, which were significantly greater than the lowest C1D1 treatment by 116.05%, 81.39%, 114.95%, 70.44%, and 65.79%, respectively. (3) The C3D3 treatment had the highest relative chlorophyll content and water use efficiency. The C1D3 treatment（25 cm diameter, 25 cm high black plastic nutritional cups） had the highest soluble protein and soluble sugar content, net photosynthesis rate, and stomatal conductance; there were no appreciable differences between the treatments in terms of intercellular CO2 concentration and water use efficiency. (4) In terms of biomass, blooming stage and diameter, relative chlorophyll content, net photosynthetic rate, and diameter growth, black root-control containers outperformed other container types. (5) The comprehensive analysis score ranking for each index affiliation function method is as follows: C3D3>C1D3>C2D3>C3D2> C2D2>C1D2> C2D1>C3D1>C1D1, the most suitable seedling containers for the cultivation of 2-year-old purple-leaf L. indica container seedling cultivation are the 2.5cm diameter and 2.5cm high black root-control containers.