Research was initiated to investigate early establishment characteristics and germination pattern of Kentucky bluegrass (KB, Poa pratensis L.) under natural room temperature and to analyze differences between alternative and natural conditions for a practical application. Fifteen cultivars of KB were evaluated in the study. Daily and cumulative germination pattern were measured and analyzed on a daily basis. Differences were observed in germination percentage, germination pattern, days to the first germination and days to 75% germination. Germination percentage was variable with cultivars at the end of study. It was 75.75 to 90.25% under natural condition. There were considerable variations in early germination characteristics and germination pattern among KB cultivars according to germination conditions. The first germination in all entries tested was initiated between 6 and 9 DAS (days after seeding) under ISTA (International Seed Testing Association) condition. But it was observed between 9 and 12 DAS under natural condition, being 3 to 5 days later as compared with ISTA condition. On the first date of a germinating process, the germination rate was 0.25% to 25.00% under ISTA condition, while 0.50% to 13.25% under natural condition. Days to the 75% germination were 15.08 to 28.80 DAS under ISTA condition and 17.78 to 28.75 DAS under natural condition. Midnight II, Excursion and Midnight were the fastest cultivars under ISTA condition, while Odyssey the fastest one under natural condition. Regardless of germination condition, the slowest cultivar was Voyager II, being over 4 weeks to 75% germination percentage. For the most cultivars, days to 75% germination under natural room temperature condition were 1 to 8 days slower than under ISTA condition. From this study information on differences in germination characteristics and pattern among cultivars would be usefully applied for KB establishment such as golf course construction. Prior to on-site seeding, a comprehensive germination test is practically recommended due to a possible decline in germination capability during domestic distribution and storage after import.