Choose the right grass. If you’re putting in a new lawn, select a hardy variety or mix suited to local conditions (a neighborhood nursery or lawn-care center can recommend types that are best for your region). Grasses vary in their temperature and moisture preferences and in how well they withstand foot traffic and resist disease. If you want to start with sod, keep in mind that it’s rarely organically grown.
Test your soil. Overfertilizing can harm a lawn as much as a nutrient deficiency can. Consider having the soil tested for pH, percent organic matter, and nutrient content, including nitrogen, phosphorus, and potassium. Remember that it can take months or even years to build optimum soil and plant health.
Adjust pH, if needed. Grass does best at a pH of about 6.5 to 7.0, whereas dandelions tend to like it a bit more acidic. Adjusting pH, if necessary, can give grass the edge. Add lime to raise the pH or sulfur to lower it, basing amounts on the results of a soil test.
Add organic matter. Compost can improve the texture of any soil, sandy or clay, and encourage earthworms and soil microorganisms. Although not a fertilizer per se, it also provides some nutrients. Spread 1/4 to 3/8 inch over your lawn once or twice a year.
Use slow-release organic fertilizer. As a general rule, you need to apply about three or four pounds of nitrogen per 1,000 square feet of lawn per year. To avoid overfertilizing, take into account the nitrogen in any grass clippings you leave on the lawn, as well as the 9 percent nitrogen content of corn-gluten meal if you use it. Apply fertilizer spring and fall as needed.
Apply corn-gluten meal, if you wish. The first year, spread 20 pounds per 1,000 square feet on your lawn in the early spring and early fall. Water it in lightly, then let the soil dry out for a few days. Reduce amount used as weeds decrease.
Set your mower blade high. Although different varieties of grass have different preferences, a general rule of thumb is to mow to 3 inches. This keeps the grass long enough to shade out many weeds. Don’t cut off more than a third of the grass height at one mowing; it stresses the grass.
Leave clippings on the lawn. It’s a cheap, easy way to add organic matter and nutrients to the soil. Clippings can provide half your lawn’s nitrogen needs—almost two pounds of nitrogen per 1,000 square feet of soil each year. It’s a myth that clippings lead to thatch; a soil with an active population of microorganisms breaks down clippings quickly, as long as you don’t mow more than that one-third of height off the grass at a time.
Water an established lawn deeply and infrequently. This encourages grass roots to grow deep into the soil; there, they can still enjoy a drink between waterings as weed seedlings on the surface dry up. Water when the lawn’s color dulls and footprints stay in the grass for longer than a few seconds. Tip: Set a cup in the sprinkler zone to make sure you water an inch each time; it takes about an inch of water to penetrate deeply enough into the root zone.
Reseed. When you pull (or kill) a weed, you create a bare spot where more weeds can easily germinate. To beat weeds to the punch, reseed right away with grass.
Aerate. In compacted soil, aeration can create space for air, water, and plant roots. Be sure to add organic matter to your lawn after you aerate, filling in the holes you’ve made. You can rent a power aerator, purchase a hand aerator, or hire someone to do the job.
Monitor for pests and pathogens. If your lawn develops an infestation or a disease, don’t panic. First, identify the culprit and try to determine the underlying cause—too much water or fertilizer, say, or perhaps too little. If adjusting your horticultural practices isn’t enough, natural remedies are available. For example, you can control grubs with either milky spore (a bacterial disease) or nematodes (parasitic worms).