To get rid of crabgrass, use a preemergent herbicide to kill crabgrass seeds before they germinate. Pull out any existing crabgrass by hand, and lightly spray the lawn with a postemergent herbicide.Continue Reading
Preemergent herbicides form a shield on the soil that prevents crabgrass from growing. Use a liquid or granular preemergent herbicide to kill the crabgrass seeds as soon as they germinate. Corn gluten is an organic preemergent option that suppresses crabgrass germination and fertilizes the lawn at the same time.
Water the lawn to wet the soil, and pull out any visible crabgrass by hand.
Spray the lawn with a postemergent herbicide to kill the crabgrass after the seeds have germinated. This also kills crabgrass that is deeply rooted and difficult to pull out by hand.
Water the lawn deeply and occasionally, and encourage the growth of healthy grass by fertilizing the lawn often. Use the technique of over-seeding to fill bare spots in the lawn with grass.
Ensure that the height of the green grass is around 3 inches after mowing the lawn. This stops the crabgrass seeds from accessing the sunlight, which they need to germinate.