I'm seeing chamberbitter running wild in my lawn and landscape right now and since I'm about to obliterate it I figured I talk about my strategy for not only getting rid of the Chamber Bitter (also called "gripeweed") but how I will prevent it heading into next season as well.
Keep in mind, where I live here in Manatee County, FL we are below what I call the "frost line" meaning we are year round growing and mowing - no seasonal dormancy.
With that, chamberbitter becomes a weed that I see almost year round. I've seen it growing 5 ft tall in natural areas here in the fall time. RIght now in August, this is what the fresh crop looks like:
For those of you further north, you may not see it year round so let me talk you through the lifecycle of chamber bitter weed.
Chamber Bitter is an Annual Weed
Chamberbitter is a springtime annual weed which means it germinates from seed in the spring and grows all summer, dropping seeds multiple times during the season as it branches up and out.
If you get a good freeze sometime in the winter where you live, that will kill it off until the following spring when the seeds in the ground will germinate and the cycle starts all over again.
Just for reference, the spring time trigger for those seeds is when soil temperatures approach and cross 70F. If you want to have some fun with your lawn strategy consider downloading my free lawn care app that gives you the soil temp at your house and then lines up a custom lawn plan for you to boot. Find out more about that here.
Pre Emergent Weed Control
And since we are talking about those soil temperatures, you can get down a pre-emergent weed control prior to that 70F soil temp and stop a good amount of the chamber bitter from every seeing the light of day. pre-emergent herbicides are chemistry designed to kill young plants just as they germinate. The trick here is that you want to get them down prior to germination or it can be too late to stop them.
In the case of St Augustine grass (and Centipede), atrazine herbicide works as a decent pre-emergent control of chamberbitter. This is great because early spring is about when you'll want to start working on your lawn and one of the early applications I like to make is an atrazine weed and feed.
I've been using the Sunniland weed/feed that you can find at Lowes all over Florida. If you are outside of Florida then you'll want Scotts BonusS. These atrazine weed and feeds are excellent for that time of year because the atrazine will stop alot of other weeds as well as act on a post emergent on others.
Another pre-emergent that works for chamberbitter is active ingredient Isoxaben. It's not easy to find Isoxaben in products that are for lawns and are also safe for St Augustinegrass, but if you have chamberbitter in your landscape beds, Snapshot is a very popular choice that works quite well.
Post Emergent Weed Control
Now most of you are probably mostly concerned about the post emergent part of this plan since Im writing this in mid-August. In case you're new here, a post emergent herbicide is one that kills the weed after it has already come up. In this case, our very best choice for St Augustine grass is Celsius Herbicide. This is also the best choice for centipede, bermuda (including hybrid) and zoysia.
Celsius knocks it our fairly quickly and the best news is that Celsius has no heat restrictions so you can use it in the hottest parts of summer with no fear.
Just so you are aware, most herbicides will have a heat restriction of 85 or 90F warning you against spraying at those high heats because the turf can be damaged in the process, especially Floratam St Augustine. But with Celsius you don't have to worry about this.
The jug is a little pricey up front since it's a professional product - you do have to invest $135 for it, but the good news is that little jug will last most homeowners a good 4-5 years.
Celsius also kills a host of other weeds that we face including spotted spurge, matchweed, doveweed, Florida Pusley and many many more. It's the primary weed control that I use in my lawn during the later spring and summer.
It's easy to mix too, 1 teaspoon (tsp) into 1 gallon water plus add a surfactant (sticker). That 1 gallon of spray mix will cover 1,000 sq ft if you have to blanket spray.
Here is a quality backpack sprayer if you need one!
Note: if you don't have access to a surfactant, just use the original no tears baby shampoo. Put 1 oz of that shampoo into the mix.
So there you go, that is the way to get rid of chamber bitter in your lawn! If you're confused about this, check out Yard Care Boot Camp where I give you all the training you need!