Ortho Weed and Grass Killer RTU 24oz

Ortho’s 24-ounce ready-to-use weed killer contains 6.36% ammonium nonanoate — an organic contact herbicide that delivers visible results in 15 minutes. That’s the hook. While systemic herbicides take days to show any effect, this OMRI-listed formula approved for organic gardening starts working immediately.

Worth it for contractors handling hardscape maintenance and non-lawn areas where quick visual results matter to clients. The product targets walkways, driveways, under trees, and landscape beds — exactly where Montana contractors need fast weed control without waiting around.

Skip it if you’re looking for lawn-safe selective herbicide. This non-selective formula kills everything it touches. That’s the trade-off for organic certification and instant results.

Speed and Coverage

Acts faster than Roundup in some user tests because it works differently. Contact herbicides like ammonium nonanoate burn plant tissue on contact rather than moving through the vascular system. You’ll see wilting and browning within minutes on young weeds.

The product kills dandelions, chickweed, spotted spurge, moss, crabgrass, ryegrass, oxalis, ground ivy, and algae. That moss and algae control matters in Montana’s shaded north-facing areas where these non-plant invaders thrive in the moisture.

Apply when weeds are small and actively growing in sun above 60°F. Montana’s short growing season means timing matters — hit weeds early in June when they’re young and temperatures finally stay above 60°F consistently.

Specification	Value
Active Ingredient	Ammonium Nonanoate (6.36%)
Container Size	24 fl oz
Application Type	Trigger Spray Bottle
EPA Registration	239-2716 or 51873-2-239
Certification	OMRI Listed

Organic Certification and Professional Use

The OMRI listing changes the conversation with eco-conscious clients. Approved for organic gardening use means you can spray around vegetable gardens without contamination concerns. Montana’s growing organic farming community appreciates herbicides that won’t compromise their certification status.

The ready-to-use spray format with precise application makes it suitable for professional landscaping. No mixing, no measuring, no drift calculations. Perfect for spot-treating weeds in gravel driveways and decomposed granite pathways common throughout rural Montana.

The non-selective nature actually helps in hardscape applications. You want total vegetation control on walkways and driveways — not selective grass preservation. Safe on hardscapes means no staining or etching of concrete, pavers, or natural stone.

Real-World Performance

With 4.3 stars across 137 reviews, contractors report three consistent themes: fast results, easy trigger operation, and organic-friendly formulation. The speed impresses everyone — clients can watch weeds dying while you’re still on site.

May need re-application for tough weeds because contact herbicides only kill what they touch. Deep-rooted perennials often regrow from untouched root systems. That’s chemistry, not product failure. Set client expectations accordingly.

Spray foliage until wet but not runoff for best results. Over-application wastes product without improving kill rates. Keep children and pets away until dry — standard safety protocol that typically means 30-60 minutes in Montana’s dry climate.

Verdict

Perfect for Montana contractors who need visible results fast on hardscape and non-lawn areas. The 15-minute action time beats everything else when clients are watching. OMRI certification opens doors with organic-minded customers.

The contact-only action means repeat applications on persistent perennials. But for annual weeds in gravel driveways, moss on north-facing walkways, and quick cleanups before clients arrive, this delivers exactly what busy contractors need — speed.

Ortho backs it with a satisfaction guarantee offering money back if not satisfied. Hard to argue with organic certification, instant results, and a money-back promise.

FAQ

Does this kill weeds permanently? No. Ammonium nonanoate at 6.36% concentration is a contact herbicide that burns foliage but doesn’t translocate to roots. Perennial weeds typically regrow and need repeat applications. Annual weeds die completely if you get good coverage on all foliage.

Is this safe for lawn use? Absolutely not. This non-selective formula isn’t for lawn use — it kills grass just as fast as weeds. Save it for driveways, walkways, and landscape beds where you want everything gone.

How quickly do results appear compared to Roundup? Visible results appear in 15 minutes versus days for some systemic herbicides. You’ll see browning and wilting almost immediately on contacted tissue. Complete death of annual weeds happens within hours.

What temperature is needed for application? Apply in sun above 60°F. In Montana, that means waiting until late May or June for consistent daytime temperatures. Morning applications work best before afternoon heat causes rapid evaporation.