Gardeners often use goutweed as a ground cover because it thrives in a variety of conditions. However, goutweed's tenacity also makes it difficult to kill. A number of control methods will effectively kill goat weed. To ensure that it will not come back, employ a combination of these methods and remain vigilant so that you can stop any re-growth before it spreads.
Pull up goutweed by hand. Use a tiller or shovel to uproot the plant and its rhizomes. The best time to do this is early spring before its foliage has had a chance to feed its rhizomes and facilitate its re-growth. Spread any uprooted plants out in the sun and allow them to dry out for a few days before you throw them away.
Mow goutweed repeatedly. Like hand pulling, this will kill the foliage before it has a chance to feed its rhizomes. It may take several seasons to kill the goutweed completely, but it will stop its spread in the mean time.
Spray goutweed with a herbicide prescribed for use on this plant, such as glyphosate. The best time to spray goutweed with herbicide is when it re-grows after being physically culled by mowing or hand pulling. When the new growth is sprayed, the herbicide is much more likely to be delivered to the underground rhizomes. Follow the manufacturer's instructions when mixing and applying the herbicide. Check that any herbicide you use is safe for neighboring desirable plants.
Replace goutweed with another ground cover that will grow successfully in your area. This will keep the goutweed or any other invasive plants from establishing themselves in the area.
Monitor the previously infested patch. Any shoots that pop up should be uprooted and discarded as soon as possible.