When you plant new grass seed, you need to take care of it so that it will grow. This includes spraying it with the right kind of chemicals.
The first chemical you should spray on new grass seed is a pre-emergent herbicide. This will prevent weeds from growing in your lawn. Be sure to read the instructions on the herbicide carefully, as some only work on certain types of weeds. Apply the herbicide before you plant the grass seed.
After you've planted the grass seed, you'll need to water it regularly. But be careful not to overwater, as this can damage the roots or even kill the young plants. Once the grass has germinated and is starting to grow, you can fertilize it with a lawn fertilizer. Again, be sure to follow directions carefully, as too much fertilizer can harm your lawn.