Very carefully. You should be cautious when using any of the above methods, as any one of them could lead to you accidentally killing desired grasses and plants. However, there are selective herbicides that can target certain plants over others. Look for a product that only affects the type of weeds you want to eliminate and spares the plants you want to keep.

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. 

Mowing a lawn will, unfortunately, not get rid of clover, and it may even encourage it to flourish. Let your lawn grow to a healthy height of over 3 inches and then set your mower blades no lower than this level. Higher grass will cut out the light that clover loves and discourage it from spreading.

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.