The weather, kids, and pets can be tough on lawns. Lack of water, too much heat, wear & tear, and other problems can make it look worn and thin. You can help reinvigorate your lawn by overseeding. In the north, spring and fall give you the ideal conditions for cool-season grass seed: cooler temperatures and more moisture. In the south, late-spring through mid-summer provide ideal conditions for warm-season grass seed. The following are simple steps to overseed your lawn.