Soil temperatures play a key role in germination. Cool season grass seed needs soil that is at least 45 to 55 degrees Fahrenheit. Warm season grass seed can germinate in soil that is 55 to 65 degrees. To get the light they need, sprouts must be able to reach the soil surface quickly. That's why the seeds should be planted at the surface or no more than 1/4 inch below.
A consistently moist surface will help the seed germinate faster. In addition to regular waterings, 1/4 to 1/8 inch of mulch helps soil retain moisture.
Grass seed takes anywhere from five to 30 days to germinate. To speed up the growth rate, opt for a scarified grass seed. According to North Carolina State University, the seed coating is chemically or mechanically altered and the hull will open sooner.