Overseeding Existing Lawns
Existing lawns can be improved by overseeding. New grass retains the green color longer in periods of drought due to better root establishment. Weed invasion is also minimized as the plant becomes denser. Overseeding can be done in spring or in early fall.

Overseeding Steps

  1. The first step is to mow the lawn closely. Choose a time when the lawn is dry. Remove any debris from the surface of the lawn before mowing.
  2. Rake the lawn using a tine rake to remove and break up layers of dead matted grass or thatch. The process is known as scarifying/verticutting (vertical cutting) and can be made easier using a machine.
  3. If the ground is compacted, it needs to be loosened. It can be spiked with a fork to a depth of at least 6 inches (15 cm). A machine on larger areas can also do this job. This will improve the root growth and the drainage on heavy soils.
  4. Select a suitable mixture of lawn seed. In principle the mixture should contain the same species as the origin of the original lawn in order to avoid differences in appearance.
  5. Remix the seed and plant by hand or machine. The seed should be divided in 2 portions, one portion to be seeded in one direction and a second portion to be seeded in the other direction to ensure even distribution. Ideally the seed should be planted after the ground has been well irrigated by rain. This will give the seed adequate moisture to start with.
  6. Feed the lawn with a quality lawn fertilizer (high nitrogen in spring, low nitrogen in the fall).
  7. The lawn can be top dressed with a thin layer of a mixture of sand, peat, and loam; proportions will be dependent on soil type. This will result in denser grass growth.
  8. Rake the area so that the seed is in contact with the soil and the topdressing is worked down into the grass. This will improve germination. Lightly roll if possible.
  9. If dry weather follows overseeding, irrigate with a fine spray keeping the seedbed constantly moist.
  10. When the grass is 2 to 3 inches (5 to 8 cm), the first mowing can be done with a high cut. Trim lightly and gradually lower blades to an ideal cutting height of 1.25 to 1.5 inches (3 to 4 cm). Mow regularly but try not to remove more than 1/3 of the growth at any time.