Learn which plants thrive in your Hardiness Zone with our new interactive map!

How to Prevent Crabgrass

By Charmayne Smith ; Updated September 21, 2017

Crabgrass is an annual weed that can be a homeowner’s most pesky lawn problem. With germination periods of up to six months, crabgrass can quickly overpower your desired grass, robbing it of its moisture and nutrients. Though it may be impossible to prevent all crabgrass, a few preventative steps can help reduce the growth of these unsightly patches.

Preventing Crabgrass Growth

Use pre-emergent herbicides during the early spring months. Crabgrass germinates from early winter through mid to late summer. Once it begins to root and bloom, crabgrass can be quite difficult to eliminate. Spraying your lawn with pre-emergent herbicides will reduce, if not eliminate, the growth of crabgrass. If your lawn was overcome with many crabgrass patches the year before, spray your lawn with two separate treatments, once in the early spring and again in the early summer.

Promote a dense lawn with vigorous lawn growth by applying a high nitrogen lawn fertilizer in the early spring. Do not wait until late summer to fertilize as the fertilizer will promote the growth of the crabgrass. It is important that all fertilization be completed during the crabgrass’ germination period (January through May, early June) and not during its blooming period (July through early September).

Water your lawn until the soil becomes moist. A vigorous growing lawn is also promoted with proper irrigation. The water should reach the roots of the grass, which allows for proper nutrient consumption and moisture. Do not water your lawn again until it begins to show signs of drought. This can be seen when you walk across the grass, and your footsteps remain.

Hand pull crabgrass patches immediately. Do not wait to address a small patch. Crabgrass is a fast- growing weed that can expand its patch size in just a few days. Pull the grass from the root, and discard or burn it immediately. Don't leave the pulled patch lying around because it can quickly reseed in a new location. Cover the area with mulch to prevent the leftover seeds or roots from re-seeding.

Mow your lawn frequently, keeping the height between 2.5 and 3 inches. Mow the lawn twice per week during spring months to keep up with the avid growing season. Summer months may only require you to mow every week or two.

Clean your lawnmower’s blades after each cut. This will reduce the spread of crabgrass seeds and pollination. Carefully remove debris and grass from the blades, and wipe the blades with a disinfectant that does not promote rust.


Things You Will Need

  • Pre-emergent herbicide
  • Lawn Mower


  • Cut your lawn immediately before applying a pre-emergent herbicide. Do not water for at least 48 hours after application. Make sure that rain isn't in the forecast.

About the Author


Writing professionally since 2004, Charmayne Smith focuses on corporate materials such as training manuals, business plans, grant applications and technical manuals. Smith's articles have appeared in the "Houston Chronicle" and on various websites, drawing on her extensive experience in corporate management and property/casualty insurance.