Clover is a common lawn weed. And although it is fairly easy to get rid of clover in a grass lawn, physically removing it is only the first step to eradicating it for good. Clover can only take a foothold in lawns that are thin and growing on soils with low levels of nitrogen. To keep clover from coming back next year, you must strengthen your lawn.
Remove the clover in an organic lawn by hand. Use a hand tiller to uproot the clover and loosen the soil where it grows. When removing the clover, make sure that its root system and any loosened seeds are removed as well. Then loosen the underlying soil to a depth of 3 inches.
Remove clover with a broad leaf herbicide. If physical removal of clover is not for you, spray a broad leaf herbicide prescribed for white or red clover (and listed as safe to use on lawns) on any patches you find in your lawn. Once the clover is dead, remove the plants by hand and discard them. Then loosen the soil in the underlying patch to a depth of 3 inches.
Spread a 1-inch layer of aged compost over any bare spots in the lawn.
Seed the bare spots. Sprinkle grass seed in the bare spots at the rate dictated by the packaging label (if no rate is given, apply 1/2 ounce per square yard). Then pat the seed down firmly with your hand to make sure that it has good contact with the soil. By thickening the lawn in this manner, you will prevent the clover from gaining a foothold again. Keep these patches moist until the grass germinates. When it reaches roughly 3 inches in height, you can resume mowing the lawn.
Spread a slow-release 4-1-2 fertilizer over the lawn in the fall. Follow the manufacturer's application rate for the type of grass growing in your lawn. This will increase the nitrogen content in the soil, thicken your lawn and prevent clover from taking root again.