Grass seeds—indeed, grass in general—can be categorized by whether the seeds do better in cool season areas (northern states) or warm season areas (southern states). There are some states in between that make up what's called the transition zone, where neither type grass seed will be ideal. Lawn gardeners there have to choose grass seed carefully. Besides dividing grass seed by suitability to temperature regions, they are divided by whether they're annuals or perennials. Most seed for lawn is perennial.
Kentucky bluegrass seeds germinate slowly, taking up to 28 days to do so. Though it's slow to establish itself, it rewards the patient by providing a perennial lawn of blue-green grass that is low maintenance and can handle cold winters, when it goes dormant. It also goes dormant when weather is hot and dry. This grass likes sun, and wants regular watering and feedings. It doesn't like the shade, so buying it in a mixture with seeds like creeping red fescue, which can handle shade, makes for a better lawn if the sun is patchy. Kentucky bluegrass can also grow in the transition zone.
Red fescue seeds are commonly added to seed mixes, providing a grass that germinates quickly while other grasses take their time, enjoying shade and cool areas where other grasses can't thrive and doing this without being aggressive. Besides its use in a mix, fescue is used in places like hills, mountains and campgrounds, where it still looks pleasing when not mowed. Red fescue is a cool season grass that also grows in the transition zone.
Perennial and annual ryegrasses are fast germinators, so they often are used in mixes to provide a lawn cover while other seeds are getting going. Besides providing quick lawns, these seeds have some strong advantages. They are easy to sow—you can just throw them by hand where you want them—and the grass is hard-wearing, low maintenance and non-aggressive. Lawns can be established with ryegrass alone, though even the perennial is short-lived compared to other grasses, with an average life of three years. The seed is useful for "overwintering" in southern climates. (In the south, grasses go brown in winter, so seeding a lawn with ryegrass in the fall—overwintering—produces green to tide the winter over until the other grasses can come back again.) Ryegrass is actually a cool season grass.
Centipede is a low maintenance, warm season grass that can handle being sown in infertile soil, including the sandy soils of Florida. It can take a few freezing dips without being killed off, but it is a warmth and light lover, and really is a southern grass. As a slow-growing grass, it will take a while to establish a lawn, but that same slow-growing nature means less mowing. Nematodes can ruin centipede grass, and mature centipede sometimes fails to thrive. These problems are often due to mismanagement of the grass. Often people don't follow fertilization and mowing guidelines, leading to grass problems.
Bahia is a warm season grass that starts easily from seeds, when many warm season grasses must be grown from plugs. The dark green grass is disease and insect resistant, and will grow in a range of soils, even if the soil is clay, sandy, infertile and dry. In fact, its thick growth crowds out many weeds. Its growth also means it will need frequent mowing. Bahia needs full sun—abundant in the south—and is drought resistant. A hardy, uncomplaining grass, Bahia is coarse textured. The Pensacola variety can be grown in the transition zone.