Can I Put New Grass on Top of the Old One?

Preparation

• The new seeds need something to grab hold of and mowing the lawn helps loosen it for them. Set the lawn mower to the lowest setting so that it cuts the grass as low as possible. If the lawn has more than a 1-inch layer of thatch, dethatch it. Dethatchers can be rented from the big home improvement stores or rental companies. Use a rake to clean up the clippings left behind from mowing and the excess thatch brought to the surface while dethatching. Walk over the lawn and fill low spots with top soil so that the surface is level. Finally, aerate the lawn with a core aerator. These are also available for rent.

Planting

• Determine the rate of seed required for the size of your lawn. Most seed packages have a rate chart on the back. Calibrate your seed spreader at the appropriate rate and walk across the lawn, spreading the seed as you go. Spread twice the amount of recommended seed on bare spots. Use a rake to blend the seeds into the top of the existing turf and the soil beneath. A lawn roller works, as well.

Water and Fertilize

• Spread starter fertilizer over the seeded area according to the rate suggested for overseeding, listed on the label. If the weather is hot, lay down a 1/4-inch layer of peat moss to protect the seeds. Water the area to a depth of 6 inches and keep the soil moist at all times while the seeds germinate. You may need to water several times a day during the establishment period. Keep people and pets off the area until the seeds have sprouted and the lawn becomes established.

Maintenance

• Until the new grass seedlings are well-established, they have a shallow root system, which is subject to drying. Keep the top 1 to 2 inches of soil moist for the first three to four weeks. If the weather is hot, dry or windy, you may need to water lightly every day -- with 1/16 to 1/4 inch of water per day. As the roots grow, decrease the frequency but increase the depth of irrigations.