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How Late Can You Kill Lawn Weeds in Fall?

October 7, 2013

I have had great success killing lawn weeds in fall.  As long as your daily temps are reaching a high of 45 degrees or more the day you spray, you can kill pesky perennial weeds like Dandelion, Clover and Ground Ivy (Creeping Charlie), as well as annual weeds like Chickweed and Henbit.  Kill them this fall and they will not be in your lawn next spring.

There are various Ortho Weed-B-Gon products depending on where you live.  Click here to see your options.  There are also special Roundup weed controls that can be used on lawns without killing your good grass.  Click here to see your options.

Note:  If you planted grass seed this fall, it is best to wait until the new seedlings have been mowed 4 times before you apply weed killers.

Fall is a great time to kill Ground Ivy, also known as Creeping Charlie

Fall is a great time to kill Ground Ivy, also known as Creeping Charlie


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  1. Anthony permalink

    Hello when is the latest you can spread Scotts Winterguard Fall Fertilizer plus Weed Control? I live in Rhode Island.

    • Hi Anthony… You can spread WinterGuard plus Weed Control on any day that the high temps are going to be at least 50 degrees. It is best to apply to moist foliage on a day when rain is not forecasted.

  2. Dave Hampel permalink

    Hello Ashton:
    We bought a foreclosed home that was empty for 2 years. The clover and crab grass has taken over the lawn. In the spring I seeded with Scotts grass seed and the patch seed. My neighbor is seeding his lawn now. We are in Pennsylvania and the temps are in the 70s still. I read that Scotts crab grass anti-emerging treatment is good to apply in early Spring but what should I do now? Oct. 10th. I have found on other lawns that Fall grass seed works well and is strong by the Spring but I am afraid a good seeding is not going to be enough to drown out the clover.
    Thanks in adavnce for your help.

    • Hi Dave
      Your crabgrass will die with the first killing frost. Your clover will continue to thrive. It is getting late to seed now in your area even though you still have warm temps. The reason is you would really want some good root growth prior to cold weather. Since it is late to seed and since grass seed does not like weed controls, take the approach of feeding your lawn now using Turf Builder WinterGuard with Weed Control. This will help knock back your clover while feeding. Apply to moist foliage first thing in the morning on a day when rain is not expected. You could do a second feeding just prior to Thanksgiving with WinterGuard. I think you will be surprised at how your good grass fills in with two feedings before winter. Then next spring you can prevent your crabgrass using either Turf Builder with Halts (can not be used when seeding in spring) OR Starter Lawn Food with Weed Preventer (can be used when seeding in spring).

      • Dave Hampel permalink

        thank you very much for a plan of attack and for taking the time to address the question. I will do exactly what you recommend and in sping use the turf building starter lawn food with weed preventor and seed it again.
        Kind Regards

  3. Dixie Ball permalink

    I want to replace my whole back yard grass. Is it best to remove the grass now before the snow or wait and do everything In the spring? The lawn is 25 years old not level and full of weeds and now I’ve seen slugs also.

    • Hi Dixie
      Tell me where you are located and I can give you more specific suggestions.

      • Dixie Ball permalink

        Hi we live in Ottawa Canada and over the last couple of years the grass has got a lot more weeds manyly because we can’t spray anything usefull any more on them. Also my husband has often commentes as it’s a pain to cut as the ground is uneven. Now it is a very small yard.

      • Hi Dixie… Thanks for telling me where you are located. You should wait to remove your existing lawn next spring prior to sodding or seeding. That way you will not end up with a big muddy mess over the winter.

      • Dixie Ball permalink

        Ok thanks I will check back in the spring to find out what we need to do and use so we can once again have a nice yard.

  4. Addison permalink


    I live in Oklahoma and I seeded my lawn with fescue and fertilized the first week of october. The house we live in has only been ours for 6 months and creeping charlie and crab grass is an issue. I used the weed-b-gone max crabgrasskiller in august and have seen a lot of it die but the creeping charlie is still looming, but not as much. Should I do another feeding in Novemember with some sort of weed killer in it or should I just stand pat until spring and use HALTS?

    • Hi Addison
      Yes, it would be a good idea to feed your new fescue around mid-Nov with Turf Builder WinterGuard. Once your new grass has been mowed 4 times you can spot spray your Ground Ivy again with Ortho Weed B Gon MAX. Plan on feeding in early spring around the time of your first mowing with Turf Builder with Halts Crabgrass Preventer. Good luck with your new lawn.

  5. Chris N. permalink

    Hey Ashton,

    I put down Scotts Turf Builder Winterguard with plus 2 weed control about 4 weeks ago. I noticed a lot of my weeds turned purple and I think that’s the weed control taking shape. But being in Arkansas the weather can act funny and it’s not gotten cold here yet. I believe the Charlie weed is appearing in my lawn now (mainly on the unsodded side of the yard as the house is 4months old). Should I go ahead and pull all these weeds or simply trust the winterguard to do it’s job?


    • Hi Chris N… I have seen Ground Ivy and other weeds turn purple with weed controls applied this time of year and the weeds did not come back in spring. If you have some that are still green, you can spot spray them with Ortho Weed B Gon MAX plus Crabgrass Killer.

  6. Jessica permalink

    I know this is an old post, hopefully you get this. But its still goin to be cool for a bit and I am wanting to put more gravel in my driveway but want to kill the grass first. My neighbor’s yard is taking my driveway, and the rest is a big muddy mess spotted with more grass and weeds. I was wanting to use the salt method to kill the soil but wasn’t sure how cold it cani be for it to work or if rain will make it not work also. I’m really wanting to kill the stuff before I lay more gravel but I can’t wait to lay the gravel. I like to take the non toxic approach to dealing with stuff like this whenever possible. I’m located in Southern Indiana. Thanks for any help you can give me on this if you get this. 🙂

    • Hi Jessica
      The most effective method would be to spray any existing grasses and weeds with Roundup Extended Control Grass & Weed Killer when the mid day temps start to get into the 50’s on a regular basis. This product not only kills existing weeds when they are growing (that is why it is best to have higher temps than you get in winter in Indiana), it also has a preventer to kill weed and grass seeds as they sprout. Not sure how well the salt method would work. If you put it down heavy enough to kill existing growth and keep new plants from germinating, I would think you may get some runoff when the salt dissolves that could injure other plants in the area. Good Luck.

  7. help it is late december and i have alot of weird weeds taking over my yard!!! killing my grass can i weed and feed now?? again in spring?

    • Hi Lisa
      Most areas are too cold now to kill weeds. Where are you located an do you know what kind of grass you have?

  8. I live in North Carolina and I want to spray for weeds. Is it okay to do so. Will I be able to seed and fertilize my lawn this fall too.

    • Hi Cora Dodd
      This is a good time to spray your weeds. Make sure you pick the Ortho Weed B Gon that matches your grass type so you will only take out the weeds and not the grass. (Depending on where you are in NC: Ortho Weed B Gon MAX plus Crabgrass Killer can be used on Fescue, Bluegrass, Bermuda and Zoysia lawns; however if you are near the coast and have Centipede or a St. Augustine grass lawn pick a weed control that can be used on these grasses). You can feed your grass (and this would be a good thing to do). Grass seed is not compatible with weed controls (you can not seed until a month after spraying which would put you kind of late to seed).

  9. Mark Kaz permalink

    Hi Ashton. I realize that this post is old but I figured O would give it a shot. I live in Virginia Beach, Va and have bought a new home. Its currently the end of January. The entire yard for the most part is a collection of all sorts of different weeds and very little grass. I would like to spring seed and seed in the fall. My question is what can I do now and plan for the future to accomplish this goal. Super Trimec now? any other suggestion or info would be great. Thank you.

    • Hi Mark Kaz
      Sorry it has taken me a couple of days to answer your questions… I was in a location with very little internet access. Since you have a new home I will first give you a run down on the types of lawns in your area. In Virginia Beach folks have Fescue lawns that stay green all winter and can tolerate a fair amount of shade. In full sun these lawns do ok if you are able to water during dry periods. The key is to feed Fescue three or so times between the end of August and late November and only once in mid to late Spring. The other alternatives in your area are Bermuda and Zoysia. These lawns are brown in the winter, however they tolerate full sun better than Fescue during your summer conditions. Bermuda does not like any shade, however Zoysia can tolerate some light shade. Bermuda and Zoysia like to get the first feeding when you are starting to see about 50% green up in early spring from the winter brown color. Then feed every two months through the end of September. Fescue is best seeded in early fall so it has ample time to develop strong roots before summer, however the second best time is early spring. Scotts Heat-Tolerant Grass Seed Blend is a good choice. Bermuda and Zoysia can be seeded in late spring. Scotts has both of these grass seed blends available using very good varieties for your area. You can spray broadleaf weeds, like dandelions and other creeping non-grassy weeds anytime the daily high temps are getting into the 60’s. You can use Ortho Weed B Gon MAX. You can seed the areas you spray a month after treating. If you seed fescue, you will want to use a special lawn food when seeding that prevents crabgrass, such as Scotts Starter Lawn Food plus Weed Preventer (this product can not be used when seeding Bermuda or zoysia). If your weeds are grasses, there is not a weed control that will kill them without killing your existing good grass. You will need to spray Roundup once or twice (it will kill your existing grass). You only need to wait a week before seeding after using Roundup (do not use the Roundup that kills and prevents growth for a full year). Killing your entire lawn is drastic, especially if you have a lawn that has been neglected (not fed for the past year or so), you may find that killing the weeds and regular feeding really brings back your existing grass and you can put seed down in the thin areas to speed along the process. Good Luck… hope my long answers help.

  10. Steve permalink

    Hi Ashton,

    My wife and I moved into a new home last year. The house is located in NJ, has an acre of grassed area, and the property was originally a fruit tree orchard. The lawn is generally healthy( the prior owner was a Master Gardener)

    We performed a soil analysis last year and everything is ok

    I am planning to thatch the lawn this fall( not sure the last time this was done) and would like to overseed- is thatching enough to prepare the soil for seed, or should I also core aerate? I’m planning to do this in early September. I.m also planning to apply Weed B Gone as a pre emergent in late October

    Your thoughts are appreciated


    • Hi Steve
      There are two ways to deal with thatch once it gets to a thickness of a half inch or more (less than a half inch is not really a problem that needs to be addressed). You can figure out your thatch thickness by cutting a plug out of your lawn and measuring the thatch thickness from the side view. The first method is core aeration, which does not tear up your lawn. The second method is using a dethatching machine that depending on how low you go could tear up your lawn to some extent. Fall is a good time of year to do this. Regarding seeding, if your existing lawn is in pretty good shape, then seeding after aeration would be ok. If your lawn is not good, then dethatching and aeration would help more of the seed to come in contact with your soil. Another option is a slit-seeder that plants grass seed just below the soil surface of an existing lawn. There is only one weed control from Scotts that is compatible with seeding: Turf Builder Starter Lawn Food for New Grass with Weed Preventer. Other weed controls have restrictions on the label for using prior to or after seeding. Hope this helps. By the way, since you stated that your lawn was in good shape and after you do a couple of feedings this year, you may find that you will not need to seed this fall.

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