Active ingredient
Atrazine
Triazine (photosystem II inhibitor, Group 5)
A residual triazine herbicide with an unusual property for a lawn product: it works both before and after a weed emerges, which is why the Southern weed-and-feed bag is built around it.
What it does
Controls the winter annual and broadleaf set that dominates a Southern lawn out of season — annual bluegrass, chickweed, henbit, dollarweed and clover — on the two grasses that tolerate it. It stays active in soil, so one application covers a germination window rather than a single flush.
What it does not do
It is not a general lawn herbicide and it is not selective by latitude. Both labels we read close the sites list to warm-season turf: bahiagrass, bluegrass, the fescues, bentgrass, ryegrass and dichondra are injured by it. And however well atrazine performs on maize, a turf label listing centipede and St. Augustine is not a corn product — the sites list is closed.
The label constraint people miss
Two constraints beyond the grass list. Atrazine reaches groundwater, and one label states verbatim that users are advised not to apply it on sand and loamy soils where the water table is close to the surface and the soil is very permeable. And the permitted grass list is not the same in every state: the weed-and-feed we review is a master label whose bermudagrass use is removed from bags printed for Florida, so read the list on the bag in your hand rather than the one on a web page.
Products we review that contain it
Every product below is here because we opened its label — on EPA's own database or the registrant's — and read Atrazine in the ingredient statement. Registration numbers are on each product's page.
Weed & Feed for Southern Lawns
Scotts Turf Builder Bonus S Southern Weed & Feed₂ (29-0-10)
★★★★☆ (4/5)
The one weed-and-feed that is safe on St. Augustine — and the only sensible choice on a Floratam lawn, where the standard bag is prohibited outright.
Best for: St. Augustine, centipede, zoysia and carpetgrass lawns with broadleaf weeds throughout
$30–$38
View on Amazon
Selective Pre- and Post-Emergent Herbicide (concentrate, warm-season turf)
Southern Ag Atrazine St. Augustine Weed Killer, 32 oz
★★★★☆ (4/5)
The mainstay herbicide for St. Augustine and centipede lawns, and the one whose availability depends on which state you live in.
Best for: Weed control on established St. Augustine or centipedegrass, where your state permits atrazine
$14–$19
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Guides that use Atrazine
- Dollarweed: The Weed That Tells You About Your Water
- Best Weed Killer for Centipede: The Sensitive One
- Best Weed Killer for St. Augustine: The Cultivar Decides
- Lawn Fertilizer Safe for Well Water: Rate, Not Ingredients
- Poa Annua: How and When to Kill Annual Bluegrass
- Best Weed Killer for Lawns: Match It to the Weed
Buy for the active, then read the label anyway. Two products with the same active are not interchangeable — concentration, labelled sites and species tolerances all vary, and a three-part registration number means a narrowed label. How to read one in two minutes. Where our page and your container disagree, the container is the legal authority.