These roots, if not removed entirely, will grow again through the new sod. You will need to kill the weeds before you can till the soil. If you do not kill the weeds first, the rototiller will tear the weeds into many pieces and scatter them throughout your yard. This will lead to even more weeds growing up through your new lawn.

Spray or sprinkle a 2.4-D, MCPP, or Banvel herbicide on your lawn. Follow manufacturer instructions for the correct application method. Never allow any of the herbicide to remain on your sidewalk or driveway. Use a broom to sweep any herbicide granules onto the lawn. Use a garden hose to spray off any liquid hydroponics fertilizer from sidewalks. Allow the herbicide to sit on the lawn for the time indicated by the manufacturer.

Pull up the shurbs by hand if you have trees or plants in your yard. It is exceptionally difficult to control herbicides. They get down into the soil and can destroy trees or other plants that share the soil. If you choose to remove the roots by hand, use a shovel to get at the roots. Do not leave any of the roots on the soil. This can be tough with large-rooted perennial weeds. Annual weeds should come up relatively easy.

Till the lawn using a rototiller. If you do not have a rototiller, you can rent one from most hardware stores. Run the rototiller over all of the lawn area; this will loosen and cut up any remaining roots in the soil. Rake the entire lawn area with a garden rake. Be sure to get out all of the dead or leftover weed roots. Do not throw the dead weeds back into the grass or in a compost pile. Place all weeds into a garbage bag and throw them away.

Plant your sod immediately after removing all weeds. If you leave the soil exposed, more weeds will take root in the soil. Keep your new sod healthy and thick to avoid more weeds taking root. Healthy grass will choke out most weeds. Remove any weeds that do emerge by hand to get the entire root.