Methods for reseeding a lawn include overseeding, during which owners spread new seed over the existing grass, or killing everything before starting again from scratch. Choosing the correct method for a particular lawn depends on the health of the existing plants and the density of the weeds that invade the yard.
Overseeding is a good approach for a mature lawn. Older grass plants slow their reproduction after about four to five years. Adding new seed to the lawn helps to establish new plants that produce more of the green blades of grass that homeowners desire. Overseeding the lawn late in the growing season gives the grass seed two to three months to germinate and establish itself before the first killing frost. Overseeding by hand works for small areas, but using a fertilizer spreader provides more even coverage for larger lawns.
Killing and restarting a lawn is never the first option. Before making this choice, owners should have a soil test to see what nutrients to add to the soil. Dethatching, applying weed killer in problem areas and fertilizing can often save a lawn. However, if these steps leave a lawn with more than 60 percent weeds at the beginning of the next growing season, starting over is often the only choice. After killing everything and preparing the soil by removing the dead grass, tilling and raking, landscapers apply seed evenly and work to establish a new, weed-free lawn.