Your Roundup Has Gotten Worse. Here's What Changed.

Blame it on habit or marketing, but picking up Roundup almost comes instinctively to many gardeners whenever they spot weeds in their landscapes. Considered highly effective, it's often treated as synonymous with glyphosate, its most notorious non-selective, systemic active ingredient. But it turns out many Roundup products today actually lack glyphosate, especially the newly reformulated versions.

If you have recently entered a Home Depot aisle or looked for top-rated weed killers online, you might still find familiar packaging — Roundup's signature blue-lidded white bottle, complete with name and label. A closer inspection, however, might reveal a red or blue bar stating "Exclusive Formula" on the front packaging. And this change is found across several offerings, including Roundup Weed & Grass Killer, Roundup Dual Action Weed & Grass Killer Plus 4 Month Preventer, Roundup Dual Action 365 Weed & Grass Killer Plus 12 Month Preventer, and their concentrated versions.

If you've been paying attention to the class action lawsuit filed against Bayer (the current owner of Roundup), you'll know there are concerns about glyphosate's safety. For this reason, you should think twice about using this popular weed killer. While the manufacturer maintains its products are safe when applied per the instructions on the label, to counteract future litigation liabilities, it's reformulating the products approved for residential use. Instead of glyphosate, they now contain varying combinations of fluazifop-p-butyl, triclopyr, diquat, or imazapic. First made available in 2023 and marketed as safer store-bought weed killer alternatives to glyphosate, they continue to share shelf space with older formulations until stocks run out (though old formulas are no longer in production).

It bears mentioning that Roundup's exclusive formulas are EPA-approved and are clearly labeled with newer restrictions and application guidelines. However, if you've been mistaking them for their older variants and using them as usual without re-reading the label, it can create adverse consequences, both for your health and garden. An advantage of glyphosate is that it lacks residual herbicidal activity in the soil, allowing for safe replanting shortly after application. In other words, you could start planting right after the formula dried, generally in a day or two. However, the hazard profile has noticeably shifted after reformulation, with newer ingredients, including fluazifop and triclopyr, exhibiting residual activity and requiring longer wait times before you can plant out a flower patch. For Roundup Weed & Grass Killer, you must wait at least a month before planting conifer shrubs and trees, 14 days for non-conifers, and a week before turfgrasses (though check the packaging label for specific instructions). Moreover, you can't spray it on edible patches or around grazing lands.

And given the different make, the approved plant and weed list has changed, as have the treatment symptoms. You could tell glyphosate was working from the foliage turning yellow and slowly dying over a fortnight. Now, expect to see faster results, though symptoms would include twisting of stems and leaves along with some purpling and yellowing in plant tissues. Accidental spread of the chemicals is more harmful to surrounding vegetation with these new formulations, as some formulations are additionally absorbed from roots, not just the foliage.

Newly formulated weed killer includes diquat, which is more toxic than glyphosate — a Friends of the Earth investigation posits that diquat exhibits around 200 times glyphosate's acute toxicity level for mammals . It's believed that certain aquatic species, like walleye, are highly sensitive to diquat even at approved label rates. It's also harmful to earthworms, honeybees, and many birds. Plus, it can be fatal to humans if absorbed into the skin, consumed, or inhaled repeatedly or over a long term, so full protection is non-negotiable. In fact, given its harmful effects on human organs, it isn't approved for use in the EU and the UK, though the EPA still has it on its approved ingredients list.

Roundup's Dual Action variant additionally includes imazapic, which stays even longer in the soil that glyphosate. It too has lost approval as a plant pesticide in the EU. While it effectively kills weeds, it does so by creating a chemical barrier in the soil, which keeps the area barren for a full year. Worse, it poses a greater risk of plant injury from drift and is not recommended around sensitive ornamentals. The same Friends of the Earth report alleges that exclusive Roundup formulations can be nearly 45 times more toxic than glyphosate ones, though Bayer refutes these claims, insisting their products are safe if applied consistent with the label. Going forward, be sure to read the label before purchasing any Roundup products, so you're prepared for formulaic changes.