When it comes to post-emergent weed control, ALWAYS read the label. Some weed controls have important considerations, such as heat or seeding restrictions, that you want to make sure you are aware of before spraying.
For our cool season folks, a great post-emergent option for you is Bayer Advanced All-In-One Lawn Weed & Crabgrass Killer, however, it has a 90º daytime temperature max, so please be aware of that.
For our warm season folks, we recommend Image for Southern Lawns. It also has a 90º temperature max, which has a heat restriction of 85º for St. Augustine lawns.
This heat restriction means “below 90 when you are actually spraying” so you could apply these products in the very early morning or the later evening and be just fine. We actually prefer the evening since temps will continue to fall overnight after you spray, whereas morning, be logical. Don’t spray when it’s 87 and will be climbing to 90 in the next 20 minutes. Play it cool and no harm will come to the lawn.
Another consideration that cool-season DIYers are going to want to keep in mind during summer weed control, is fall seeding. You will need to read the product label to find out how long you must wait after post-emergent application to seed. If you apply post-emergents too close to your seed window, you will either kill your new seed or miss your window waiting for the time buffer to elapse. You will also want to make sure you wait long enough before you apply post-emergent to newly germinated grass seed.
Here are more examples of weed control label considerations based on the above-mentioned Bayer Advanced All-In-One Lawn Weed & Crabgrass Killer:
“Bare spots may be seeded 4 weeks after application."
This is referring to blanket applications that are done, and after the weeds are killed and gone -- those bare spots -- those can be seeded 4 weeks after with no issue. That’s really what that is saying. So if you have areas that you really have to get heavy-handed in, and hit 2 or even 3 times to kill all the weeds - just watch how close up to August you are getting when you do this. It may be better to opt out of spraying too hard after July 20 or so. According to the above, you can re-treat weeds every 2 weeks. That’s a good 6-week window you have starting right about now. Get to it!
“Newly seeded lawn may be sprayed after fourth mowing”
That’s another one we get quite often and it’s important. Just as we have to stop blanket spraying 4 weeks before seeding… we can’t start spot spraying again until the 4th mowing which is going to be SEVERAL weeks after you get the initial growth. Depending on grass type (KBG takes 2-3 weeks just to germinate, Rye is a few days) you may not be able to spray weeds again until Halloween and at that time it may be too late anyway. This is why we tell you to try and push to start in later August if you can be sure to irrigate.
Weed control in the summer is 100% possible, for sure! Just be certain to read the important information on your label so that you can knock out those weeds with confidence and peace of mind.
For more details on summer weed control, check out this blog by Allyn: https://thelawncarenut.com/blogs/news/summer-lawn-faqs-what-you-can-and-cant-do-with-your-weed-control-during-the-summer
Keywords: weed, weed control, summer