The best time to start fertilizing your lawn is in the early spring, when the soil temperature reaches 50 degrees Fahrenheit. You will want to continue fertilizing every 4 to 6 weeks after your first application.
Generally, you’ll want to plant cool-season grass seed at least 45 days before the estimated date of your first fall frost, before soil and air temperatures drop to less favorable levels. Your grasses will enjoy a full fall season, plus a second cool, growing season come spring.