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Johnson grass doesn’t look like a typical weed—it grows tall, fast, and thick, choking out your desired turf before you even realize it’s taken hold. The real frustration is that many general weed killers simply won’t touch this aggressive perennial grass, leaving you to watch it spread rhizome by rhizome.
I’m Mohammad Maruf — the founder and writer behind Gardening Beyond. I spend my time comparing the chemical compositions and application methods of specialty herbicides, studying aggregated owner feedback, and digging into the horticultural data on what actually stops stubborn grass species like this one.
After evaluating the top selective herbicides on the market, I’ve narrowed down the options that actually deliver results. This guide focuses entirely on the best johnson grass lawn solutions that target the weed without destroying the surrounding turf.
How To Choose The Best Johnson Grass Lawn Herbicide
Not all weed killers are created equal, especially when the target is a perennial grass with an extensive underground rhizome system. Choosing the wrong product can waste money, damage your lawn, or simply leave the Johnson grass untouched. Here’s what to look for.
Selectivity: Protect Your Turf, Kill the Invader
The first filter is whether the herbicide is selective for broadleaf weeds or for grassy weeds. Products containing 2,4-D target broadleaves and will not kill Johnson grass. Look for active ingredients like fluazifop (in Ornamec 170) or MSMA which are designed to selectively target grassy weeds in specific turf types. Always cross-check the label against your lawn grass species—St. Augustine and centipede are particularly sensitive to some herbicides that are safe on Bermuda or Zoysia.
Delivery Method: Concentrate vs. Ready-to-Use
Johnson grass often grows in patches, requiring spot treatment rather than blanket spraying. Ready-to-use wands (like the Ortho WeedClear Comfort Wand) offer convenience for small patches. For larger infestations, a concentrate that you mix in a pump sprayer gives you better control over concentration and coverage, and is more economical per square foot. The concentrate options also allow you to add a surfactant to improve leaf adhesion and rhizome penetration.
Speed of Action and Number of Applications
Johnson grass is tough. Most formulations will stop growth within 48 hours, but full death of the rhizomes may take one to three weeks and often requires a second application. Products that claim to work in hours are typically targeting the leaf tissue, but the root system may survive. Look for user feedback about “multiple coats” or “follow-up treatments”—this is a realistic expectation, not a product flaw. A herbicide that controls the rhizome over time is superior to one that only scorches the top growth.
Quick Comparison
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| Model | Category | Best For | Key Spec | Amazon |
|---|---|---|---|---|
| Gordon’s Ornamec 170 | Selective Grass Herbicide | Landscape bed maintenance | Fluazifop-P-butyl 0.98% | Amazon |
| Target 6 Plus MSMA | Professional-Grade Herbicide | Large turf areas and golf courses | MSMA 48.3% concentrate | Amazon |
| Southern Ag Amine 2,4-D | Broadleaf Weed Killer | Broadleaf control in turf and pasture | 2,4-D DMA salt 46.8% | Amazon |
| Ortho WeedClear Ready-to-Use | Convenience Spray | Spot treatment of dandelion & clover | Multiple broadleaf actives | Amazon |
| Bonide Chickweed & Clover Killer | Ready-to-Use Spray | Chickweed, clover, and creeping charlie | Dicamba + Triclopyr | Amazon |
In‑Depth Reviews
1. Gordon’s Ornamec 170 Grass Herbicide
This is the specialty product specifically formulated for Johnson grass and other stubborn perennial grasses like Bermuda and torpedo grass. The active ingredient, fluazifop-P-butyl, is a selective grass herbicide that stops growth within 48 hours and kills the entire plant—rhizomes included—within one to three weeks. It is designed for landscape beds, meaning it reduces the risk of injury to ornamental shrubs and flowers while taking down the grass invader.
User feedback confirms it works well on Bermuda grass and crabgrass in Kentucky Bluegrass lawns without harming the desirable turf. Multiple applications are sometimes needed for heavy infestations, but the selectivity is excellent when used according to label directions. The concentrate covers a large area for the price, making it a mid-range investment per treatment.
One caution: it is not recommended for St. Augustine grass, as users reported significant damage to that turf type. Stick with Zoysia, Bermuda, or cool-season lawns for best results. The 32-ounce bottle mixes at a low rate, so it lasts through several spot-treatment sessions.
What works
- Selectively kills Johnson grass and Bermuda without harming ornamentals or Kentucky Bluegrass
- Fast visible results with growth stopping in under 48 hours
- Concentrate provides excellent coverage per ounce
What doesn’t
- Can severely damage St. Augustine grass; not labeled for it
- May require two or three applications for complete rhizome kill
2. Target 6 Plus MSMA Turf Herbicide
MSMA (monosodium methanearsonate) is a powerhouse active ingredient that has been used for decades on golf courses, sod farms, and highway rights-of-way for controlling grassy weeds. Target 6 Plus delivers MSMA at 48.3% concentration in a 2.5-gallon jug, making it the highest-volume, highest-potency option in this lineup. It is particularly effective on goosegrass, crabgrass, nutsedge, Bahia grass, and of course Johnson grass.
Users consistently report seeing results in two to three days when mixed at 1 to 2 ounces per gallon of water with a surfactant and AMS. The product is thick and high quality, and a single jug can last years for homeowners with moderate infestations. It has a stellar 4.7-star rating from nearly 900 reviews, with many customers calling it the only thing that worked on Bermuda grass.
MSMA is a restricted-use herbicide in some states, so verify local regulations before purchasing. It can stress hybrid Bermuda grass into dormancy but generally recovers, and it is safe on seeded Bermuda. The price reflects the professional-grade quantity and concentration—an investment for serious infestations.
What works
- Extremely fast-acting on Johnson grass, goosegrass, and nutsedge
- High concentration means a single jug provides immense coverage
- Proven track record on golf courses and sod farms
What doesn’t
- Restricted-use herbicide in some states; check local laws
- May temporarily yellow hybrid Bermuda grass under heavy application
3. Southern Ag Amine 2,4-D Weed Killer
This is an important product to understand because it represents a common mistake. 2,4-D is a selective broadleaf herbicide—it kills dandelions, spurge, clover, and burdock but will not touch Johnson grass or any other grassy weed. That said, if your lawn has a mixed infestation of broadleaf weeds alongside the Johnson grass, this is an economical option for the broadleaf component.
With a 4.4-star rating and nearly 8,000 reviews, Southern Ag’s 2,4-D is a proven, fast-acting concentrate. Users report visible wilting of broadleaf weeds within hours and death by the next day. The low use rate of 1 to 4 pints per acre makes the 32-ounce bottle go a very long way on pastures, rangeland, and turf.
It is critical to pair this with a dedicated grass-specific herbicide if Johnson grass is the primary target. Alone, it will not solve the problem. But as part of a comprehensive weed management program, it is a budget-friendly and reliable tool for the broadleaf half of the equation.
What works
- Extremely fast knockdown of broadleaf weeds—visible results in hours
- Very economical with low use rates per acre
- Highly concentrated; one bottle covers large areas
What doesn’t
- Completely ineffective on Johnson grass or any grassy weeds
- Can drift and damage desirable broadleaf plants and ornamentals
4. Ortho WeedClear Lawn Weed Killer Ready-to-Use
The Ortho WeedClear with the Comfort Wand is built for convenience. The battery-powered wand delivers a targeted spray that makes spot-treating dandelions, clover, and crabgrass quick and easy without mixing or cleanup. It covers up to 20,480 square feet per gallon.
User reviews are overwhelmingly positive for its ease of use and speed. Many report that dandelions brown and die within two weeks after a single application, with no damage to surrounding lawn grass. The product is safe on Bermuda, Fescue, Kentucky Bluegrass, Ryegrass, and Zoysia when used as directed.
The limitation is that it is designed for common lawn weeds, not aggressive perennial grasses like Johnson grass. For a homeowner dealing primarily with broadleaf invaders and only a small patch of Johnson grass, this can be part of a broader strategy, but it should not be relied upon as the primary Johnson grass elimination tool.
What works
- Battery-powered wand makes spot application effortless and precise
- Fast results on dandelions and clover in under two weeks
- Safe on multiple common turf grass varieties
What doesn’t
- Not formulated for Johnson grass or other perennial grassy weeds
- Some users received returned units with missing parts or used batteries
5. Bonide Chickweed, Clover & Oxalis Killer
Bonide’s formulation uses a combination of dicamba and triclopyr, which are effective on a wide range of broadleaf weeds including chickweed, clover, creeping Charlie, and poison hemlock. It is a ready-to-use spray that targets weeds without harming lawn grasses when applied correctly.
Users find it works well on chickweed and clover but note that it is ineffective on crabgrass—and by extension, Johnson grass. The product is nearly odorless and clear, which is a plus for residential use. For heavy infestations, the ready-to-use format can become costly, and the included hand sprayer is considered weak for large lawns.
Like the Ortho product, this is not a Johnson grass solution on its own. Its role in a Johnson grass management plan is to clean up the broadleaf competition so that a grass-specific herbicide can work more efficiently on the target weed.
What works
- Effective on creeping Charlie, clover, and chickweed
- Safe on lawn grasses when used as directed
- Clear and nearly odorless formula
What doesn’t
- Does not kill crabgrass or Johnson grass
- Hand sprayer is subpar for large areas; prefer pump sprayer
Hardware & Specs Guide
Active Ingredient Chemistry
The active ingredient determines what the herbicide kills and what it spares. Fluazifop-P-butyl (Ornamec 170) is a grass-specific ACCase inhibitor that targets the growing points of grassy weeds. MSMA is an organic arsenical that disrupts photosynthesis in grassy weeds. 2,4-D, dicamba, and triclopyr are synthetic auxins that cause uncontrolled growth in broadleaf plants. Matching the chemistry to the weed species is the single most important decision.
Concentration and Mixing Ratio
Higher concentration products like Target 6 Plus MSMA (48.3%) offer more applications per dollar but require careful measurement. Lower concentration ready-to-use sprays are convenient but expensive per treatment area. For Johnson grass, a concentrate that allows you to dial in the right ratio for spot spraying is usually more effective because you can add a non-ionic surfactant to improve leaf wetting and rhizome absorption.
FAQ
Will 2,4-D kill Johnson grass in my lawn?
How many applications does it take to kill Johnson grass completely?
Is MSMA safe to use on St. Augustine grass?
Final Thoughts: The Verdict
For most gardeners battling a Johnson grass invasion, the best johnson grass lawn solution is the Gordon’s Ornamec 170 because it offers a perfect balance of selectivity, speed, and safety for landscape beds and cool-season turf. If you have a larger property or a heavy infestation and are comfortable with professional-grade chemistry, grab the Target 6 Plus MSMA for its raw power and decades of proven results. And for those dealing primarily with broadleaf weeds alongside a small patch of Johnson grass, the Southern Ag Amine 2,4-D paired with a grass-specific spray will cover all your bases economically.