Typically, grass seeds germinate within 2 weeks of planting, with most sprouting within about 10 days. However, some varieties can take up to 30 days to germinate, and the climate and conditions of the growing area play a large role in determining how efficient the germination process will be.
If your grass seeds are taking longer than expected to grow, make sure to keep the soil slightly moist by sprinkling the soil a couple of times per day, if necessary.