How to Prevent Crab Grass


Crabgrass is a vigorous growing weed that can appear in almost any landscape or lawn. The weed thrives in lawns with poor aeration, thin turf and compacted soil. It begins to germinate when soil temperatures begin to average 50 to 55 degrees Fahrenheit and produces hundreds of seeds that are spread by the wind and rain. Though this aggressive weed can quickly overpower a lawn, certain measures can help in preventing, if not reducing, the presence of crabgrass.

Step 1

Apply a pre-emergent herbicide to the lawn, in the early spring, once the soil temperatures average 40 to 45 degrees Fahrenheit. Distribute the herbicide evenly across the lawn. Follow the instructions carefully. Ensure that the weather is dry, with no expected rain, before completing the application.

Step 2

Water the lawn slowly and deeply to promote a strong, deep rooting system. Provide the lawn with 1 to 2 inches of water in the early morning or late evening to avoid sun evaporation. Irrigate only when the lawn begins to show signs of drought stress, such as lack of luster, slight change of color, and loss of blade resiliency. Increase the irrigation schedule during dry, hot periods and decrease during rainy periods.

Step 3

Feed the lawn regularly, providing about one pound of fertilizer per 1,000 square feet. Use a well-balanced, slow release fertilizer, such as a 40-40-40 or 30-30-30 combination. Distribute the fertilizer evenly across the lawn and water in thoroughly. Apply the fertilizer in the early morning when temperatures are below 85 degrees Fahrenheit to avoid burning the lawn.

Step 4

Mow the lawn regularly so that no more than one-third of the blade requires removal at any one time. Keep the lawn between 2.5 and 3.0 inches high during the spring and summer months. Reduce the height by one inch during the fall months.

Step 5

Promote good aeration throughout the lawn to keep crabgrass at bay. Keep the lawn free of debris. Always rake up the mowed debris immediately after mowing. Dethatch the lawn every one to two years to promote good circulation throughout the soil. Prevent the potential of compacted soil with these steps to reduce the potential for crabgrass growth.

Step 6

Remove any crabgrass flowers as they appear. Use a shovel or hoe to loosen the soil around the crabgrass and root. Pull the crabgrass from the soil by hand. Ensure that the root is completely removed from the soil to prevent regrowth. Dig up the remaining root from the soil, if necessary.

Things You'll Need

  • Fertilizer
  • Pre-emergent herbicide
  • Water


  • Purdue Extension and University of Illinois Extension: Control of Grabgrass in Home Lawns
  • University of California: Crabgrass
  • UIUC: Crabgrass
Keywords: preventing crabgrass, dethatch the lawn, crabgrass flowers

About this Author

Charmayne Smith is a business professional and freelance writer. She has worked in management for successful organizations since 1994. Smith draws on her business background to write articles, and her work has appeared in a variety of online outlets. She holds a degree in business from Cleveland State University.