Apply a slow-release fertilizer to your lawn on Labor Day and Halloween. The fall is also a good time for controlling weeds, removing thatch and planting new seed.
Fertilize shady lawns with less nitrogen, because they grow more slowly. In the fall, weeds are busy absorbing nutrients for winter, so they die faster after you spray them with herbicides. Remove thatch, which is dark brown plant material, if it is more than 1/2 inch thick. Aerating is also best done after Labor Day. In early fall, grass grows quickly and there are fewer weeds. If you plant grass seed at this time, it becomes established quickly.