Roundup: The herbicide active ingredient in Roundup is glyphosate, which if sprayed on the lawn will kill not only the weeds but the lawn. … When used properly it will not kill the desirable turfgrasses in the lawn. This is a selective herbicide that controls specific weeds, but not lawn grasses.

What to do if Roundup gets on grass?

If you unknowingly damaged your lawn with an herbicide like Roundup, you’ll have to do some physical renovation to the lawn. You’ll want to go ahead and remove the dead areas of lawn before more weeds move in to take its place. Then re-sod the patches or re-seed the areas, depending on the type of grass in your lawn.

What kills weeds but not the grass?

2,4-D is the more common selective herbicide which has been researched for decades on its safety and effectiveness. Using it properly has minimal risks and is extremely effective at killing weeds without killing your grass.