An experiment was established at the Institute of Forestry Campus in order to standardize an optimum container size for raising quality seedlings of Acacia auriculiformis and Chickrassia tabulatris. Five different sizes of polybags were tried for three months time in the nursery. The parameters of seedlings like total height, collar diameter, root length, root diameter, dry weight of root and shoot etc. were measured at the end of the experiment. The finding showed that the polybags of T4 treatment (30.5 x 15 cm size) produced quality seedlings of both the species within three months time and the size may be used in quality seedling production purposes for a short time. But, for large scale plantations, the polybags of T2 treatment (23 x 15 cm size) is the optimal size for raising quality seedlings of Acacia auriculfiormis and the polybags of (30.5 x 15cm size) is optimal size for Chickrassia tabularis.