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Crabgrass Questions

April 22, 2013

Here are answers to four of the most common crabgrass questions I am getting now:

Is it too late to prevent crabgrass?

Answer:  To do the best job preventing crabgrass, you should have spread your crabgrass preventer by the time all the yellow blossoms fall off the forsythia bush, or by the time lilacs begin blooming, or by the time you are starting to see lots of dandelion puffballs.  If based on one of these indicators you conclude it is too late to apply your Turf Builder with Halts, allow me to offer some additional info for you to consider.  Crabgrass seeds germinate over several weeks like waves hitting a beach.  The first germination is where the soil warms up first, like next to a driveway or sidewalk, or a south facing slope.  If you had lots of crabgrass last year, and you have not gotten your crabgrass preventer down yet, you might still consider making the application as soon as possible even though you are seeing one or more of the nature indicators I mentioned.  That is because you can still prevent the later germinating crabgrass if you act fast.

I am seeding this spring.  Can I prevent weeds like crabgrass?

Answer:  If you plan on seeding this spring, I have good news.  There is a crabgrass preventer that is compatible with grass seed:  Scotts Starter Food for New Grass plus Weed Preventer.  You will get about 6 weeks of weed prevention which will allow your new grass to get a head start before being overrun and choked out with weeds like crabgrass.

I already put down crabgrass preventer… when can I seed?

Answer:  The Turf Builder with Halts Crabgrass Preventer directions state that you should not plant grass seed for 4 months after application, which means you will need to wait until the end of August to seed.  However, I have two answers depending on the size of the lawn area that needs new grass seed.

1). If you only have a few small areas you want to seed, I have seen folks get around the fact that they have a crabgrass germination barrier in those spots by cultivating the soil to a 4 inch depth (to disrupt the crabgrass barrier), then mixing in an inch of compost like Scotts Turf Builder Lawn Soil to further dilute the preventer, and then seeding with Scotts EZ Seed.

2). If you have a large area you want to seed, the first recommendation is not practical, so you really need to wait until early fall to seed.

I know I am too late to prevent crabgrass… can I still do anything to get rid of it?

Answer:  If you had lots of crabgrass last year, read my answer to the first question.  There is something to use to kill crabgrass after it is up and growing.  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 Killer on most any kind of lawn except Centipede, Bahia and the Floratam variety of St. Augustinegrass.  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.

Crabgrass Seedlings about a week after germination

Crabgrass Seedlings about a week after germination

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10 Comments
  1. Elliot permalink

    Applied scotts #1 4/17/13 here in east hartford ct. Tomorrow (4/24) plan on applying lime.Can I repeat scotts #1 in a couple weeks? Is it ok to cut grass now?

    • Hi Elliot Step 1 will give you 6 to 8 weeks of feeding. You should allow at least a month between Step feedings. Suggest you go to Step 2 for your second application. If you are worried about getting crabgrass because you had a lot of it last year, rather than putting down Step 1 again, you could spot treat any stray plants with a spray of Ortho Weed B Gon MAX plus Crabgrass Killer. The only reason I could think that you would want to put Step 1 down again is if you think it went down too light because of a spreader problem. (In other words you had more of the bag left over at the end than you thought you should based on your lawn size.)

  2. ca apptyen lawn be seeded after weed and feed is

    • Hi Al
      Your lawn can be seeded a month after putting down weed & feed. Tell me where you are located and I will give you specific suggestions.

  3. Bob permalink

    I put down app # 1 last week (blue bag) now see a weed I doe’t recognize and dandolions. How long till feed will dandlon preventive (app 2 I think) toms river NJ tx bob

    • Hi Bob
      It is typical to allow 6 to 8 weeks between feedings. You can cut this down to 4 weeks, however you would have increased mowing from the overlap in feeding from the applications. Your best option would be to spray weeds now with Ortho Weed B Gon MAX plus Crabgrass Killer and then your next feeding would be 6 weeks or so after your first.

  4. potorski permalink

    instead of using a guy who speaks scottish, why dont you guys just get scottie form star treck to sell your lawn and garden stuff. he could add special dilithium crystals to the lawn and give the lawn warp speed

  5. Anne permalink

    We live in South Central Kansas. We have a massive dandelion take over in our back yard. I would say the area is 80-90% weeds. Our front yard still has a lot of good grass and only a few dandelion spots. We have purchased Turf Builder with Halts Crabgrass Preventer and Ortho Weed Be Gone Max (bottle to attach to the garden hose) to treat the yard. We have been waiting for a day without rain to start the treatment. I know we are a little late. I noticed this weekend that the dandelions are just starting to send up puff balls. Question, do we go ahead and treat with the Turf Builder w/Halts first or use the Ortho Weed B Gone first? How close together can we use both products? Is it more important to kill the dandelions before they seed or try to prevent the crabgrass? We have a three day forecast without rain, so we want to do the appropriate step first.

    • Hi Anne Do the Turf Builder with Halts first. You can do the Weed B Gon Spray a few days later after you water or after you get rain.

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