Soil

• Wait for soil temperatures between 40 and 45 degrees Fahrenheit to plant cool-season grasses in the spring, according to Purdue University. Soil should be 50 degrees Fahrenheit or warmer before warm-season grasses should be planted.
  
  

Air

• Plant cool-season grasses in the spring once air temperatures reach at least 59 degrees Fahrenheit. Warm-season grasses do well when they are planted in 60- to 65-degree Fahrenheit weather, according to the University of Connecticut.
  
  

Water

• Frequent, light watering keeps grass seed moist, which is necessary for germination, according to Ohio State University Extension. Times throughout the spring season when frequent rainstorms can help keep grass seed damp, which vary depending on your location, prove ideal for planting grass seed.