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Best time of day or weather to spray weed control like Round up or Weed B Gon.

I remember someone mentioning there was a better time to spray so that the green leaves absorb the liquid but I cannot seem to find it in the archives.

30 comments
  • 360 Sod (Donna Dixson)
    360 Sod (Donna Dixson) Buford, GA
    on Mar 19, 2012

    If you are spraying lone weeds (as in not on top of your lawn grass) Round up works better if the ambient temperatures are between 60 and 85 degrees F. Weed B Gone has a different active ingredient (2-4d) ,which you can spray over Bermuda grass at the current temperatures. It will activate faster at a lower temperature than the glyphosate(round up) active ingredient. When temperature go above 90 you are taking a risk using any weed killer because the air will move it around where you don't want it to go.

  • Kevin M. Veler, Law Office of
    Kevin M. Veler, Law Office of Alpharetta, GA
    on Mar 19, 2012

    So time of day does not matter? Plants are not more likely to say absorb moisture through leaves in morning vs evening vs noon? Just asking. I've sprayed some a few times but trying to get the most "kill" for my effort. The temp info is great. Thanks!

  • 3sonscrazy
    3sonscrazy Fort Collins, CO
    on Mar 20, 2012

    Yeah, I have always read that it should be applied in moderate temperatures and less wind and rain.

  • John Madison Landscape, Inc.
    John Madison Landscape, Inc. Orlando, FL
    on Mar 20, 2012

    We always recommend spraying weed killer after the morning dew has dissipated. That way you are not diluting the chemicals even more than they already are. The temperature is also important and we suggest the same as Four Season Nursery did above.

  • Robin W
    Robin W Washingtonville, NY
    on Mar 20, 2012

    The best time of day to spray weed killer is NEVER! Pesticides are carcinogens and neurotoxins and do not belong where other living things are. Investigate alternative weed controllers, such as vinegar, boiling water or mulch.

  • John T
    John T Skokie, IL
    on Mar 20, 2012

    ..there are some control products that use natural sources. Best time for broadleaf weeds is Fall when they are storing up nutrients for the winter.

  • Barbara R
    Barbara R Bryan, TX
    on Mar 20, 2012

    Never! This stuff is not selective on plants that it kills and though it says otherwise, it can be toxic to pets and humans. Consider mixing a gallon of strong vinegar with 2 ounces of orange oil plus a squirt of dish detergent. This is a natural herbicide that may take more than one application but is much safer than chemical herbicides. It works best during the sunniest, hottest part of the day.

  • Donna Marie P
    Donna Marie P Buffalo, NY
    on Mar 20, 2012

    Vinegar works very well ... a great alternative to chemicals

  • Garden Inspire
    Garden Inspire Bountiful, UT
    on Mar 20, 2012

    Ideally - never. There are better ways to control weeds. If you do use lawn weeds killers (most contain 2,4d) follow precautions and use when the temperatures are between 70 F & 90 F. Below 70 F they won't work well and above 90 F they can damage your lawn. I would recommend keeping all people and pets off for at least 24 hours. http://gardeninspire.webs.com/pesticidesherbi...

  • Joan W
    Joan W Everett, WA
    on Mar 20, 2012

    Please be kind to the earth and don't use Round Up or similar products. With all the info online recently about the evils of these products and what Monsanto is doing, please research and be a responsible gardener.

  • Angela K
    Angela K Aledo, TX
    on Mar 20, 2012

    @ Donna, do you use white vinegar, do you spray it on, & does it hurt grass or shrubs?

  • Mary M
    Mary M Kirkville, NY
    on Mar 20, 2012

    what natural alternative do you suggest for killing poision ivy or poison oak?

  • Candy J
    Candy J Erwin, TN
    on Mar 20, 2012

    Does it matter if it is white or brown vinegar? I really like this idea.

  • Bill B
    Bill B O Neals, CA
    on Mar 20, 2012

    Spray after dew is gone, no rain or sprinkling for 24 hours,warm sunny temps if possible.

  • Margy M
    Margy M Manchester, KY
    on Mar 21, 2012

    I am going to try vinegar tomorrow, I have brown and white. May use both!

  • Darryl D
    Darryl D Jonesboro, GA
    on Mar 21, 2012

    The "natural" alternative suggestions are making me want to gag.

  • Brenda A
    Brenda A Aiken, SC
    on Mar 21, 2012

    Post from Pinterest- 34 oz. spray bottle-1/2 c. salt, squirt of dishwashing liquid,fill up the balance of bottle with PICKLING vinegar.SHAKE SHAKE Shake. KIlls weeds, but also grass and other vegetation. So best to use in areas that you want to eliminate everything.

  • Terrry S
    Terrry S Central Point, OR
    on Mar 21, 2012

    Kevin, looks like you are a lawyer so you may appreciate hearing that the law requires you to read the label and the label tells you the conditions under which you should spray. I'm not trying to be the weed control police or anything and of course we all know the cops aren't going to show up to bust you for not reading a label. But there is a liability issue you might appreciate. If the label tells you not to spray when it's windy, but you go ahead and spray on a windy day because you didn't know that & the pesticide spreads over to your neighbors prize roses and kills them (or worse yet, you do damage in an agricultural area or to ground water) you are liable. Knowledge is power and I really recommend reading the label for your own safety as well as the sake of everything around you. If the label on the container isn't readable they are all available on the net these days. Vinegar users also need to be careful. Just because it is natural doesn't mean it can't hurt you if you have sensitive skin. Do not use more than 5% acidity (normal household stuff). Vinegar is broad spectrum which means it kills whatever it comes in contact with, including shrubs & grass. Vinegar only kills topically. Spray it on a leaf, especially in the sun, and it will burn the area it contacts. It will not spread to the roots or to other leaves and kill them, but sometimes the death of the leaf will lead to starvation of the rest of the weed; sometimes not.

  • Angela K
    Angela K Aledo, TX
    on Mar 21, 2012

    @Brenda,if I want to use in grassy areas or in beds, what should I use?

  • Betty Brady
    Betty Brady Richland, WA
    on Mar 21, 2012

    I would not use Round-up. Toxic to everything, including humans. Going green, like using vinegar is better for you and the environment.

  • Brenda A
    Brenda A Aiken, SC
    on Mar 21, 2012

    @Angela K- BAD NEWS...Your Hands ! I put a book on cd and sit down and commune with nature ! LOL It is a pain but when done thoroughly at the beginning of the season, that takes care of it, for the most part. I always wait and put down my new mulch afterwards, then DONE! I have gravel paths around my flower beds. That is where I use it. Also where you would have pavers.

  • Barbara R
    Barbara R Bryan, TX
    on Mar 21, 2012

    You can use the 5% or 9% white pickling vinegar found on grocery store shelves. It will probably be plant based. You can also find 20% strength which will probably be petroleum based but is still better to use than Round Up. Add 2 ounces (4 tablespoons) of orange oil plus a squirt of liquid dish detergent. (That helps it stick to the plant.) Use in the hottest part of the day.

  • Margy M
    Margy M Manchester, KY
    on Mar 22, 2012

    I used a bottle each of white and brown vinegar in a garden sprayer yesterday. It was in the 80's here, and within two hours the weeds were turning yellow. Haven't looked yet this morning. So far so good though.

  • Margy M
    Margy M Manchester, KY
    on Apr 20, 2012

    Well, the vinegar doesn't kill my tough hillbilly weeds, folks! It stunts their growth a few days but then they come back stronger than ever!

  • Candy J
    Candy J Erwin, TN
    on Apr 20, 2012

    How would it work on my mulch? Now I have dang grass and weeds growing thru my mulch.

  • Maire.l.bond
    Maire.l.bond
    on Jun 15, 2013

    Don't plants have different biochemical processes during different times of the day, though? Wouldn't that affect how RoundUp works?

  • Cynthia
    Cynthia Dawsonville, GA
    on Jun 21, 2013

    Spray only when it's full sun and not due to rain within 24 hrs. Roundup works fast. Be careful when spraying close to shrubs and flowers. Always best to just pull those.

  • Dale B
    Dale B Tyler, TX
    on Jun 24, 2013

    I have tried the vinegar solutions and have had limited results. If you are killing tough weeds especially some that tend to be woody or have a waxy coat on the leaves, Roundup brings good results. It is impractical to try to use home remedies when you are doing large areas. Just be responsible and use as directed to prevent damaging surrounding plants.

  • Allen Marsh
    Allen Marsh
    on Jun 28, 2015

    How long after rain ends do you wait to apply?

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