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How to Kill Crabgrass in Your Lawn NOW

May 18, 2012

Used to be the only way to rid your lawn of crabgrass was to prevent it from starting to grow in spring and then to dig out any stray crabgrass plants during summer before they produced thousands of seeds.  Now Ortho has a very effective crabgrass killer that not only kills crabgrass after you have it growing in your lawn, but also takes out hundreds of other kinds of weeds without harming your good grass.

You can use Ortho Weed-B-Gon MAX plus Crabgrass Control on most any kind of lawn except St. Augustinegrass, Centipedegrass, Bentgrass or Bahia.  If you have Bermuda you may get some temporary yellowing after spraying.  It is best to spray on a day when temps are between 45 and 90 degrees with no rain or irrigation for at least an hour after spraying.  You can plant grass seed 4 weeks after spraying.

Click here to get more details on Ortho Weed-B-Gon MAX plus Crabgrass Control.

Crabgrass Seedlings about a week after germination

Finger-like seed heads on Crabgrass show up soon after mowing during summer

From → Uncategorized

59 Comments
  1. James Cunningham permalink

    Very informative.

  2. Ajoy Adhikari permalink

    I sprayed the crabgrass killer on my lawn couple of months ago and did not do anything yet.

  3. Aaron Palmer permalink

    Will Scotts Bonus S Souther Weed and Feed kill my crabgrass or do I need to put something else down before I use it. I have centipede grass.

    • Hi Aaron
      Bonus S prevents crabgrass and can also kill young crabgrass. The main thing with your Centipede is to limit your feelings to twice a year. If you have already fed recently kspot spray your crabgrass with Ortho Weed B Gon MAX plus Crabgrass control. You can expect some temporary discoloration of your grass. If you have not fed recently the Bonus S will feed control weeds. Good luck with your lawn.

  4. Brandon Simmons permalink

    Q4 Plus is a very good product to use for crabgrass in certain types of lawn grasses. I bought some at my local COOP (Lowe’s or Home Depot doesn’t carry it) and sprayed it about a week ago on my Zoysia lawn. The crabgrass is already turning yellow and curling up, so it seems to be working. This herbicide is very strong, so definitely read the directions before applying. It kills broadleaf weeds as well as a few other grassy weeds. Good Luck!

    • Brandon Simmons permalink

      Aaron,

      Sorry, but I just now realized Q4 Plus is not recommended for use on Centipede grass. That is what it says in the directions. You might could cut what you mix in half or something and try it on a small spot and see what happens.

      Good luck to you!

  5. Kathy permalink

    I am only a homeowner and was here under crabgrass to ask, can you treat with crabgrass killer when it is over 90 degrees and sunny or is it better to wait until it cools off?

    • Hi Kathy
      It would be better if the temps were only getting into the 80’s as you would have less of chance of causing damage to your good grass.

  6. I have an area about 40 feet x 200 feet totally infested with crabgrass. There is no sod / grass planted in this area. Obviously I want to kill this grabgrass before I lay sod. I have heard MNSA will work. What recommendations do you have?

    • Hi Ray
      Rather than going with MSMA to clear the area of crabgrass prior to sodding, I suggest you go with Roundup since it will not only kill the crabgrass, but also other weeds in the area. You will then be able to sod in a week. Also suggest you put down Scotts Starter Fertilizer the day you sod.

  7. Darryl permalink

    i have bahaha grass and and more then half of my back yard is invested with crab grass and other weeds what would be a good product for me to use and could i use it on my whole yard by the way i live in florida

    • Hi Darryl
      You can spray the crabgrass in your bahia lawn with Ortho WeedBGon MAX plus Crabgrass Killer, however it is best to pick a day when the temps will not reach the 90’s as you could see some discoloration of your bahia. I know this can be tough this time of year in Florida. If temps are not coorporating, them be aware of the temps when you “spot treat the crabgrass and other weeds. Good luck!

      • Pete permalink

        FYI – According to the Scotts website address shown below – Ortho Weed B Gon MAX plus Crabgrass Killer should never be used on Bahia lawns.

        http://www.scotts.com/smg/goprod/ortho-weed-b-gon-max-crabgrass-control/prod70146/

      • Hi Pete
        Thanks for your comment. I see the “do not use on Bahia” comment on the product overview page that you are citing, however when you look at the actual PDF product label found by clicking the link on the lower part of the page, Bahia is listed as one of the grasses the product can be used on. So, I am now confused like you. I will send an email to some folks and try to find out which reference is correct. Thanks again for helping us clear this up.

      • Hi Pete
        Just wanted to let you know and thank you for helping us correct a mistake on our website and in my blog postings. Our website is correct: Ortho Weed B Gon MAX plus Crabgrass Killer can not be used on Bahia. The PDF product label on the Scotts site that I was using to write my blog is an old label. The current revised label with the added grass restrictions will replace the outdated label on the site.

  8. Dave permalink

    Hi I have an area I planted Blue Stem prairie grass it is just peaking up,,but I have some grab grass and other weeds. It is early August. Should I wait for spring to ,attack the problem or now? I am located in southern Maine.

    • Hi Dave
      I do not have a good suggestion for you now, however I would be concerned that the new crabgrass will choke the Blue Stem before it gets going good. I would be afraid to use Ortho WeedBGon MAX plus Crabgrass Killer as it could kill your young Blue Stem while knocking out your other weeds. You could try spraying a small area to see. The crabgrass will die with a killing frost, however even for Maine that is many weeks away. Next spring you could prevent the crabgrass before it germinates. Sorry not much help.

  9. Christine Stevenson permalink

    What can I use against crabgrass. I live in the Ottawa Valley. Any help you can offer will be appreciated.

    • Hi Christine
      Your crabgrass will be killed by frost later this fall. For Canada, I do not have a crabgrass control you can spray without killing your good grass. However, if you have patches that you want to kill in order to plant good grass seed, you can spray with Roundup. Roundup will kill your crabgrass and any other grasses so spray only in the areas where you do not have much good grass you are trying to save. The good thing is you can plant grass seed in those areas 7 days after spraying Roundup. You should rake out the crabgrass to help rough up the soil prior to seeding. Good Luck with your lawn.

  10. Spencer permalink

    We had our yard stripped to install an irrigation system and new sod was planted with blended kentucky blue grass. The irrigation system is set to water for 20 minutes daily. Our yard is full of crabgrass. Is there anything we can use before the fall to get rid of this pesty weed? We mow our grass high at 3″. We appreciate your assistance.

    • Hi Spencer
      You can spray crabgrass with Ortho Weed B Bon MAX plus Crabgrass Killer. However, understand that crabgrass is harder to kill now since it is more mature this time of year. Your crabgrass will die with the first good frost. The sprinklers set to water everyday is ok while you are waiting for your sod to get established. Once your sod is well rooted, about a month from now, you will want to set your sprinklers to water long enough to put down a half inch of water twice a week. This deeper watering will encourage deeper roots. Feed your lawn a couple of times this fall.

  11. I continue doing battle with crabgrass every year, despite my best efforts or spraying, pulling & trying to prevent because my next door neighbor’s yard is full of it & continues getting into mine & eventually exhausting me. Any tips? (Besides moving?)

    • Hi human Triumphant:
      I would like to give you some specific tips and application timing suggestions. What city do you live in and is your crabgrass alive now or dead (killed by frost)?

      • I live near the Tennessee/Georgia border, with mild temps. It doesn’t seem as if anything ever kills it – or it multiplies too quickly for me to notice (though maybe I got some luck with this morning’s frost).

  12. HumanTriumphant:
    Thanks for giving me your location. I think it is likely you have had a good frost. We have had one in Atlanta about a week ago. Once you have a killing frost, your crabgrass will look like the picture in this blog posting:
    http://tipsfromashton.wordpress.com/2011/11/14/crabgrass-id-after-frost/

    If you determine that you now have dead crabgrass from a killing frost, timing your application of crabgrass preventer is very important. In your area, the application should be made in March. Read this blog posting for timing suggestions:
    http://tipsfromashton.wordpress.com/2012/02/16/crabgrass-prevention-timing-is-everything/

    If your “crabgrass” is alive after a killing frost, you likely have one of the perennial grassy weeds that often gets confused for being crabgrass. Read this blog posting to check out some common culprits:
    http://tipsfromashton.wordpress.com/2012/03/29/how-to-kill-crabgrass-look-a-likes/

    Our Crabgrass preventers generally prevent about 90 to 95% of the crabgrass from growing, so there may be a stray plant or so that can be killed in June with Ortho Weed-B-Gon MAX plus Crabgrass Killer. This spray works best on young crabgrass. Spraying at the end of summer on mature crabgrass is not as effective.

    Hope I have helped you figure this one out.

  13. John permalink

    I live in the Orlando FL area. New house with new sod, just a little over a year old. Crab grass is taking over in one area. I have St Augustine Floratam. so cannot use the new Ortho product. What are my options. Home Depo said use weed and feed and use a catcher to avoid spread of seeds.

    • Hi John
      The advice you got at Home Depot is correct. The Bonus S Weed & Feed works best on crabgrass when it is applied early in the season. The only other thing I suggest is to spread some straight Halts Crabgrass Preventer on your lawn next January. This product contains no feeding which is good for that time of year. It will only prevent new crabgrass seeds, not control those plants that do not die out if there is a mild winter. And, it can be used on all varieties of St. Augustinegrass.

  14. John permalink

    Thanks, I checked the Ortho Website, it says not to use on Floratam.
    “Do not use on Floratam (a variety of St. Augustinegrass), Centipede or Bahiagrass lawns.”
    http://www.scotts.com/smg/catalog/productTemplate.jsp?proId=prod70146&itemId=cat50064&icid=hp1_mm_p_owk

    Will Scotts Southern Weed and Feed have any affect?

  15. Mike permalink

    Hi,
    I am in Eastern NC. We have centipede grass and my entire front of the lawn is infested BIG TIME with crabgrass. That stuff grows out of control. I just mowed five days ago and I need to mow already. About two weeks ago I laid down Scotts BONUS S Southern Weed and Feed. Can I use this stuff now or should I wait? What do you suggest? Everyone around me has a nice lawn except for me.

    • Mike permalink

      Also, if I do use this stuff, obviously (according to what you say) my grass will turn yellow. How long after I use this stuff can I put Scotts Green MAX down? Most importantly, will that help my cent come back?

      • Hi Mike (again)
        GreenMax would be a good product for your Centipedegrass, however I would wait 6 to 8 weeks after your last feeding with Bonus S. Good luck with your lawn!

    • Hi Mike
      Crabgrass in your area would have just sprouted in the past few weeks. From your description, I am wondering if you have one of the perennial grassy weeds that would be larger this time of year, like Dallisgrass. It is safe to spray Ortho’s Nutsedge Killer on Centipedegrass and this product kills a few of the grasses like Dallisgrass. I would certainly try it in a small area first. In any event, back to your question. You should not feed your lawn any more frequently than every 6 to 8 weeks, and with Centipedegrass, the first feeding of the season should not be before the grass is at least 60% green coming out of the winter and not more than 2 or 3 total feedings a year. Feed it more than that and it starts to decline. The best solution for crabgrass in your type of lawn and in your area, would be to prevent it with an application of Scotts Halts (without a feeding) in the middle of March.

  16. Edward Chavez permalink

    My name is Edward, I have about 4000 sq. ft. of tifway bermuda that is getting a lot of crabgrass. I cut my lawn 3 times a week but over the last 2 year the crabgrass is moving in fast. My question is, can I kill it, or I’m I stuck with it?

    • Hi Edward
      You can spray the crabgrass with Ortho Weed B Gon MAX plus Crabgrass Killer. There are no restrictions for spraying onto Bermudagrass. I always like to spray a small area to see how the weeds die during the next week to get an idea how heavy I need to spray to kill the rest. This also allows me to see if my grass is a little bit sensitive to the dose, which can sometimes be the case with Hybrid Bermudagrass. I think this is a good idea when spraying because this is not as precise as putting down granules with a spreader. Remember next Feb/Early March to put down Scotts Halts Crabgrass Preventer (the one that does not contain Turf Builder since the time to prevent crabgrass is before the time to do the initial spring feeding on Bermudagrass.

  17. HI Ashton,
    I live in Md, my crab grass roots are deep, I have pulled for several hours, used weed feed and crab preventer. I have used specticide spray, but will try the Ortho Weed B Gon Max plus crab grass killer. My question is will it kill the roots down 3 inches?

    • Hi John
      I am wondering if you are digging crabgrass or a perennial grass that has an extensive root system. The reason I am questioning is in your area right now crabgrass would be a seedling with about 4 to 6 blades and would be rather easy to pull up. Crabgrass is an annual. The crabgrass cycle is: germinates in spring, grows and spreads during summer, dies with the first killing frost in fall after depositing thousands of seeds to run the cycle again the following year. This is why a crabgrass preventer in early spring can stop the cycle from repeating. The Ortho Weed B Gon MAX plus Crabgrass Killer will not work on perennial grassy weeds. The only thing that will is Roundup which kills any grass, even your good grass, so this is not generally used in a lawn.

  18. Tyann permalink

    We live in Idaho and have tried two different sprays, one just a week ago on a beautiful 72 degree day and the crabgrass is still growing strong. Any advice please please please???

    • Hi Tyann
      I am wondering if the grassy weed you are spraying is really crabgrass. Crabgrass in your area would be small seedlings at this time. It should be susceptible to Ortho Weed B Gon MAX plus Crabgrass Killer. It will take a few weeks for it to die. If your grassy weed is more mature, it may be one of the perennial grasses that can get confused with crabgrass (like Timothy, Orchardgrass, Fescue, Quackgrass, Nimblewill, etc.). If that is the case, we do not have anything that will kill it without killing your good grass.

      • Tyann permalink

        Right now the only thing in our “lawn” is this crabgrass or the other weed you are saying and dandelions. It was a foreclosed home and they let everything die and this is all that’s growing.

      • Hi Tyann If the dandelions are dyeing from the Ortho Weed B Gon MAX plus Crabgrass Killer (can take several weeks) and the grassy weed is not, it is likely one of the perennial grassy weeds I mentioned. Because of the low rainfall in your area during the summer months, you might want to wait to plant new grass this fall when you have a better chance of getting your lawn established without nursing it through the summer. (One reason you are running out of time to seed now is you can not seed for about 4 weeks after spraying the Weed B Gon.) If you find that the grassy weed is not crabgrass, Roundup is the solution, however it will kill all vegetation. It may require two sprays a week apart to do the job. The good thing is you can seed the area a week after spraying. So you could do a complete lawn conversion in Late August/Early September.

  19. robert l roberts permalink

    does pastoria kill crab grass and if so when is the best time of the year to spray robert from arkansas

    • Hi Robert I Roberts
      I do not have any experience with Pastora. I do know that it is for use on Bermudagrass, which is common in many areas of your state. You may want to check with your local Cooperative Extension Service or a knowledgeable Garden Center to learn more about this herbicide and it’s use in your area on pastures and lawns. Sorry I could not be more helpful.

  20. Bridget permalink

    I spent over $500.00 of planting grass. this Mr.Bermudagrass has just taken over. Its about 95 here in texas at this point. hoping what were i put on my grass, i dont not kill my St.Augustine grass. Can you help me any kinda way…Please……

    • Hi Bridget
      Sounds like you planted St. Augustinegrass. If your lawn is sunny, I suspect you will have to allow your St. Augustine and Bermudagrass to coexist as a mixed lawn. I say this because Bermudagrass loves Texas, especially if the lawn receives a lot of sun and Bermudagrass is hard to get rid of. It grows from even the smallest piece of root that may be in your soil as well as from seed. However, the more shade you have the more you will find that the St. Augustinegrass will do better than Bermudagrass. Some of the St. Augustinegrass Weed & Feeds that you put down in spring, like Scotts Bonus S Weed & Feed will discourage Bermudagrass however will not get rid of it. I would not put this down now during the hot weather.

  21. Janey Jones permalink

    I live in Louisville ky & realize it is too late for spring care.I hope to remove crabgrass by hand if possible-can I use Ortho on empty spot and when can I plant grass on that area? I welcome any other suggestions. thanks

    • Hi Janey
      You can spray crabgrass and other weeds with Ortho Weed B Gon MAX plus Crabgrass Killer. This product will not harm your lawn. You can seed those spots 4 weeks after using this product. If there is nothing growing in the area but weeds (no good grass), you can spray the area with Roundup and then you can seed 1 week after spraying. (Some tough weeds may require two Roundup sprays.)

  22. Maria Whitson permalink

    Hello, seeking advice. We live in Ca and rarely get frost, therefore waiting for the frost to kill our growing crabgrass problem doesn’t exist. We moved into a home with an existing mature crabgrass issue and have battled trying to remove it. I sprayed Ortho Crabgrass killer today. We have sprinklers and water every morning at 5 am. What else do you suggest, considering it is mid-summer? Thanks for any advice!

    • Hi Maria
      You may need to repeat your spray of Weed B Gon MAX plus Crabgrass Killer if the first spray does not do the job as mature plants are harder to control than young plants. Be sure to put Turf Builder plus Halts Crabgrass Preventer in early Feb next year to help prevent new plants germinating from seed.

  23. NWMOBOY permalink

    I re-seeded my lawn back in June and now have crabgrass. The lawn is pretty well established but it is very dry here. No rain in weeks. Will the Ortho Weed B Gone hurt my new lawn? Also have dogs. Any harm to them?

    • Hi NWMOBOY
      Your new grass needs to be mowed 4 times before spraying your weeds with Weed B Gon MAX. Also, it is best to not spray if your temps are consistently in the 90’s. It is hard to kill weeds when they are not growing, which would be the case if you are not getting any rainfall or are not irrigating. Keep your dogs off your lawn while you are spraying. You can let them out onto your lawn once your grass has dried. Sorry, it seems I have given you more precautions than encouragement. Let me know where you are located and any info on what you seeded and I will be glad to give you more specific suggestions for late summer and fall.

  24. Jennifer permalink

    How would you apply this product if your using a 15 gallon sprayer. Ive got 4 acres I want to spray.

  25. bill swartz permalink

    I live in western Colorado and have Kentucky blue grass and crab grass keeps showing up in my yard, at least I think it’s crab grass. It’s broad leaf looking grass and it grows taller than the rest of the grass. Can you please help me? Thanks

    • Hi Bill
      The best way to tell if you have crabgrass will be if that grass dies when you get your first killing frost this fall. If that happens, your best defense will be to put down a crabgrass preventer combined with your early spring feeding next year, like Turf Builder with Halts. If the grassy weed does not die with the frost, it is likely one of the perennial grasses like coarse fescue. There is no way to kill the perennial grasses without killing your Ky Bluegrass. The option then is to very carefully spray individual weed clumps with Roundup without getting any of the spray on your good grass.

  26. Paula Nixon permalink

    I live in central California and have a sever Crabgrass problem in the back yard and a growing threat in the front. We had a sever frost last winter, which killed a lot of stuff that usually makes it through fine,including some of my good grass, but I don’t remember the crabgrass suffering. When I mow, it looks like it needs mowing two days later. It is supposed to be near 100 today.
    I am a 77 year old widow with no money to waste. Best suggestion.

    • Hi Paula Nixon
      There are two approaches to crabgrass problems. The first is to put down a preventer, which in your area would be best applied in late February using Scotts Turf Builder with Halts. The second is to kill it when it is young with Ortho Weed B Gon MAX plus Crabgrass Killer. Here is a link to info on this product:
      http://www.ortho.com/smg/goprod/ortho-weed-b-gon-max-crabgrass-control/prod70146/
      A word of caution, this product should not be sprayed when your daytime temps are above 90 degrees. Your current crabgrass should be killed with a frost. There is a crabgrass look a like called Dallisgrass that grows in the Central Valley of California that is a perennial and is not prevented or controlled. You can find pictures of it in one of my older blog postings:
      http://tipsfromashton.wordpress.com/2013/08/28/crabgrass-id-confusion/
      Good Luck with your lawn.

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