When determining when you should seed your lawn, it’s important to note whether you need cool or warm season grass. This factor can be determined depending on where you live, as cooler states like Washington and Oregon will typically require cool season, while southern states like Texas and Florida need warm season grasses.
The transition area in the middle comprising states such as Kansas or Nevada will usually use a mixture of both, so if you live in this area, make sure you pay attention to the needs of both types of grass.
The rule of thumb is to seed cool season grasses in the fall making sure that you do it before air and soil temperatures fall below desirable levels, make sure to seed all the brown spots in grass, and water thoroughly. The best time is typically about a month and a half before the estimated date of the first fall frost.
As for warm season grasses, they have to be planted in the spring, once the soil temperature reaches a higher level and there is a promise of warmer times to come. The soil temperature should generally reach at least 65 degrees about three inches below the soil surface. That way you can make sure that the grass will grow well and it won’t struggle too much with colder temperatures.