1. Fertilize at Labor Day to get your grass growing vigorously. Don't fertilize again until spring, unless the fall stays evenly cool (not cold) and moist. If that's the case, fertilize again at the end of October. You don't have to pay extra for "winterizing" fertilizers that are high in potassium because most soils in the Midwest naturally contain enough.
2. Let the lawn's growth dictate when you mow. Most grasses should be cut when they reach 3-1/2 inches. To be sure there's plenty of the plant left to feed itself, trim only one-third to one-half of the stalk (to no less than 1-3/4 inches; 2-1/2 inches is better).
3. If footprints show in your lawn for more than a second or two, or if the grass color turns purplish, it's too dry. Give your yard about an inch of water. But too much develops shallow roots. If you sprinkle only when your grass is on the verge of wilting, you encourage it to develop deep roots that sustain it better year-round.
4. Check for thatch problems, especially if your lawn started with sod laid over clay soil. Cut a 6-inch-wide triangle out of your lawn, down to the original soil. If you find that the top layer is like a thickly woven doormat and nothing grows into the lower soil, that's a problem.
5. To eliminate thatch, coreaerate your lawn. A machine pulls up hundreds of index-finger-size sections, allowing spaces for air, fertilizer and water.
6. You can pay a lawn service or do it yourself by renting an aerator. If you hire someone, make sure the aeration averages 30 holes per square foot. Doing the work yourself? Use a machine with tines 2 inches apart and go over the lawn about 10 times. Each hole should be 2-1/2 to 3 inches deep.
7. If you patch bare spots with small pieces of sod remove enough soil to set the sod level with the grass around it.
8. Use a weed killer in fall. But if you seed your lawn now, don't apply a herbicide. It will kill grass that sprouts.