How to Control Crabgrass

By: Julie Day

Crabgrass growing in lawn

How do I get rid of crabgrass? I have tried all the over the counter products, and I can’t seem to get rid of it. -Dusty

To kill crabgrass, there are two things you need to know about it:

  1. Crabgrass Is an Annual Weed: The plants themselves are killed by fall frosts, but the seeds remain on the ground to sprout anew the next spring and summer. Each plant can produce over 150,000 seeds!
  2. Crabgrass Is a Grassy Weed: As the name implies, crabgrass is a grass, as opposed to a broadleaf weed. That means that any product that kill crabgrass will also kill the grass in your lawn.

Knowing these facts, keep in mind these tips for controlling crabgrass:

  • A healthy, thick lawn is your first defense against crabgrass. Nurture your lawn, and keep your mower on the highest possible setting. Crabgrass seeds require bright sunlight to germinate, so they’re more likely to invade bare spots.
  • Water less frequently, but more deeply, to discourage crabgrass and other weed germination.
  • Use a grass catcher when mowing your lawn, to capture seed heads. Discard the clippings – you can begin composting them again once you have the crabgrass and other weeds under control.
  • Use a pre-emergent herbicide in the spring and summer to prevent crabgrass seeds from germinating. Do not aerate or otherwise disturb the “shield” provided by the herbicide. Watch forsythia and lilac bushes, since the traditional time to apply pre-emergent herbicide is between the blooming of forsythia and lilac. You may also want to re-apply the herbicide in early summer.
  • “Weed and feed” type products often contain pre-emergent herbicides, but some do not have high enough concentrations to be effective against stubborn crabgrass. If you’ve tried them without success, consider applying a pre-emergent herbicide separately.
  • Attack clumps of crabgrass as soon as you spot them, before they have a chance to go to seed. Crabgrass produces a toxic chemical that inhibits the growth of plants around it, so it will soon start affecting your lawn grass. Pull the plants by hand, or spot spray with a post-emergent herbicide such as Round Up.
  • Pull and discard the dead crabgrass plants as soon as possible, to prevent them from smothering your lawn grass.

Further Information

Julie

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6 Comments on “How to Control Crabgrass”

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  • Carol McGaity Says:
    August 2nd, 2015 at 10:11 pm

    I have a lot of crabgrass. It is hot summer 90+degrees. What should I put on the crabgrass in this hot weather to kill it or what should I put on my grass to make it healthier.



  • Darrell juba Says:
    July 12th, 2015 at 10:03 am

    I just moved to central Florida from Cleveland, Ohio, and need to fix my front lawn consisting of St. Augustine grass. Brown patches about 3 to 4ft by 5ft starting from my driveway going towards the center of the yard. A large shade tree covers most of the yard, and the grass under the tree seems fine, whereas the grass exposed to more sunlight is dying and turning brown. The soil consists of sand with a very thin layer of black soil looking dirt about a 1/16 in thick. Could cinch bugs be the problem and should I add bags of top soil to amend the soil? Is this the standard type of soil found in Lake Mary, Florida, and will St. Augustine grass flourish in a mix of top soil sand and peat moss or other organic material? Dirt and soil are much different in Cleveland, Ohio, than central Florida,so how do I correct the dying brown dead grass and dried out grass runners, which turn into dust with the consistency of dried peat moss, from continuing to invade and migrate further into my lawn?



  • Lee Says:
    September 21st, 2010 at 2:26 pm

    Thank you for the helpful tips!



  • Julie Day Says:
    December 10th, 2008 at 8:02 pm

    I’m glad you were able to read the article. If you have any more trouble viewing articles or following links, please post a comment or click the “Ask Julie” link to send an email.



  • Carol Says:
    December 10th, 2008 at 4:05 pm

    Well, after I left the first comment, then the article could be read… sigh.



  • CAROL Says:
    December 10th, 2008 at 4:04 pm

    What a worthless article. It could not be read because the formatting cut off the right hand side of the ariticle.
    Fix this please as I need this advice. thanks


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