Organic Lawn Care

A very good guide to maintaining a (relatively) weed free lawn and growing healthy soil without chemicals. From the website:

Organic Lawn Care For the Cheap and Lazy

In a nutshell:

Must do:

• Set your mower as high as it will go (3 to 4 inches).
• Water only when your grass shows signs of drought stress and then water deeply (put a cup in your sprinkler zone and make sure it gets at least an inch of water).

Optional:

• Fertilize with an organic fertilizer in the fall and spring. I recommend the Ringer brand.
• Have the pH of your soil professionally tested. Add lime if it is below 6.0 and gardener's sulfur if it is above 7.0.
• How much top soil do you have? See how deep a shovel will go into the soil. How deep can you dig a hole in one minute? If you have less than four inches of soil, you must add topsoil.

Now for the verbose details:

This is a game of competition. You want to make things favorable for the grass and unfavorable for the weeds so the grass will choke out the weeds. Naturally.