Lawn grasses are each suited to a specific growing area.
image by U.S. Department of Agriculture, DRW & Associates
Lawn grass germination is one of the mysteries of life. Once you've conquered the process, you become the sage of the neighborhood and adviser of young homeowners. The hybrid grasses that are grown in our lawns share basic rules of germination with all seeds, though; they are commanded to grow by specific natural conditions programmed into their chromosomes. The smart gardener simply matches cultural practices with the genetics and biological clock of grass.
Visit a lawn center and ask what types of grass grow best in your area. Grass seed comes in mixes of annual and perennial grasses that are combined to be successful in areas with common temperature ranges and precipitation patterns. In the continental United States, they are labeled as cool-season (for northern areas), warm-season (for southern areas) or transitional grasses (in a band from mid-Atlantic to the mountains of Arizona and Southern California. Divisions within warm and cool-season areas are based on rainfall.
Begin at the right time. Grass genetics dictate that grasses germinate when ground temperatures are between 55 and 65 degrees F. Air temperature and bright sunshine are relevant only as they warm the ground. No matter how much you water or coax that seed, it will wait until the growing medium---the soil that surrounds it---is about 60 degrees F. Seed sown too early in spring will just wait for warmth, and seed sown too late in the fall will stay dormant until the following spring.
Prepare a level, friable bed for your grass seed. Break up clods of dirt so water will drain easily through the soil, remove rocks and stones (don't worry---more will rise up later) and add at least an inch of good topsoil if your soil is heavy (lots of clay) or too light (sandy). Do not fertilize---an application of manure or compost used for soil conditioning has a gentle level of nutrients to tide growing grass over to its first application of the strong stuff.
Adjust soil chemistry if necessary. Your lawn needs a base of soil with a pH between 6.0and 7.5 to flourish. This is a pretty wide range but occasionally soil will need applications of lime or sulfur to correct levels. A soil test can establish whether adjustment is needed.
Broadcast or spread seed according to directions. More is not better where seed is concerned---seeds that have to compete for space and nutrients are less likely to germinate successfully and make lush beds of scrawny grasses. The annual grasses---the first to sprout and shelter the perennial grasses---crowd them out instead. Because the perennial grasses are next year's grass, the lawn might have to be reseeded in its second year.
Keep seeded lawns moist, not soggy. Too much water keeps oxygen---a necessary element for germination---out and suffocates the sprouts or, worse still, leads to mold and mildew. Water lightly twice a day, hope for clouds and never water late in the evening as the dew falls. Your grass seed should start to sprout, depending on variety, in one to two weeks. Be patient. Certain perennial grasses, like Bluegrass and Bermuda grass, might take up to a month to germinate.