Whether you're starting a new lawn or reviving an existing one, it helps to approach the growing of grass the way you would any other plant. A lawn is made up of thousands or millions of individual grass plants -- as many as 850 plants per square foot. All grasses may look more or less the same, but different types have different levels of insect and disease resistance; drought, shade, and foot-traffic tolerance; and temperature hardiness.
A lawn usually contains a combination of many grass types. Picking the right mixture for the conditions in your yard is essential. Just as a plant that thrives in dry soil will likely die in a boggy spot, an out-of-place grass will grow poorly or not at all. For example, cool-season grasses prefer a temperature range of 60-75 degrees and generally require less water, but summer heat can stress them. Warm-season grasses thrive in higher temperatures (80-95 degrees), but they lose their color when the mercury drops. However, warm-season grasses typically have deeper roots and can tolerate close mowing and heavy foot traffic.
After you've picked the right grass, you have to decide how to plant it. As with other annuals and perennials, you can start grass from seed or put live plants in the ground. With grass, that means sod. Sod is the quickest, easiest way to start a new lawn -- but usually the most expensive. Sod yields a usable lawn in a few weeks. You might be able to lay a section of sod yourself, but large jobs probably demand professional installation. Grass seed is generally much cheaper than sod and can be sown by a do-it-yourselfer. However, it requires extensive preparation, timing, and careful follow-up care. You'll need patience, too, because seeded lawns can take months to establish. Plus, some grasses just don't start well from seed, leaving sod or plugs -- small chunks of sod "plugged" into the ground -- as your only options.