A spot herbicide for weed control is effective at killing crabgrass and not grass, but it depends on the type of herbicide. Always check the label to ensure that your herbicide is safe for grass but tough on crabgrass. Overall, spot treatment is ideal because it puts fewer herbicides into the soil, which can damage the soil. If you’re wanting a natural remedy to crabgrass that also won’t harm surrounding grass, you can also hand-remove crabgrass or even pour boiling water or 5% vinegar over crabgrass as a spot treatment.

Weeds may grow back when pulled out if the root is not completely removed. Invasive weeds can regrow from just a small portion of remaining root, so using a weed-pulling tool can help ensure you remove the entire root. Weeds may grow back faster if roots aren’t fully removed, and incomplete removal could cause them to spread as well.

Mowing your grass regularly, especially if you’re mowing close to the ground, can help kill Johnsongrass. Frequent mowing helps limit the spread of Johnsongrass and can even deplete carbohydrate reserves in rhizomes over time. The more time you leave in between mowing, the more likely Johnsongrass is to regrow and take over your lawn. 

Noxious weeds can be poisonous or act as an irritant to humans, but not all are directly harmful. However, indirectly, noxious weeds also compete with native species, effectively affecting our local ecosystems of plants, pollinators, and other animals.