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Specs are compiled from manufacturer listings and verified buyer reviews and can change over time — please confirm the key details on the product page before buying.
Black medic (a sprawling weed with yellow flowers) acts like it owns your lawn, spreading fast and resisting many common weed killers. The trick is picking a herbicide that lists black medic on its label and spraying it while the plant is small and still growing actively. This guide compares three options that work, from a fast-acting concentrate to a broad-spectrum specialist, so you can choose the one that fits your yard without guesswork.
I’m Rikta — the writer behind Lawn Gear Lab. This guide compares the manufacturer’s published specs and patterns from verified buyer reviews, giving you each pick’s real strengths and trade-offs.
We break down the active-ingredient concentration, effective coverage, and customer-reported results for each herbicide for black medic, so you can match the product to the size of your lawn and your patience for follow-up sprays.
Our Picks at a Glance
How To Choose The Best Herbicide For Black Medic
Black medic looks like a mini clover but acts like a stubborn weed that shrugs off many common lawn treatments. Before you buy, check three things: the active ingredient, the concentration, and how much coverage your yard needs.
Active Ingredient — Quinclorac Is the Standard
Not every weed killer works on black medic. Quinclorac at 18.92% concentration is the proven active ingredient (the chemical that does the killing) that targets both grassy weeds like crabgrass and broadleaf weeds like black medic, clover, and dandelion. Look for it on the label under “Active Ingredients” rather than just a brand name.
Liquid Volume and Coverage Per Treatment
Herbicide concentrates come in bottles from 16 fluid ounces to a full gallon (128 fluid ounces). A smaller bottle may cost less upfront but treats far less area per application. Check the label for square-foot coverage and how many ounces you need per gallon of water to see the real cost per lawn.
Speed of Results vs Residual Control
Some formulas show dying weeds in 2 days, while others take up to 6 days to see the first signs and nearly 2 weeks for a full kill. Faster knockdown often needs a surfactant (a sticker-spreader that helps the liquid cling to waxy leaves like black medic’s). Slow-acting products still work — you just wait longer for the final result.
Quick Comparison
| Model | Best For | Liquid Volume | Active Ingredient | Coverage | Amazon |
|---|---|---|---|---|---|
| BASF Drive XLR8★ Best Overall | Fast knockdown + residual | 64 fl oz | Quinclorac 18.92% | 1,000 sq ft | Amazon |
| TZone SE | Pro-grade broadleaf control | 128 fl oz (1 Gallon) | Quinclorac (mix) | Up to 16,000 sq ft | Amazon |
| Pro Crabgrass Killer | Budget-friendly concentrate | 16 fl oz | Quinclorac 18.92% | Selective coverage | Amazon |
In‑Depth Reviews
1. BASF Drive XLR8 Crabgrass Killer
Our pick — over 4★ from 200+ verified ratings; the strongest balance of quality and price.
The 64-ounce concentrate that knocks down black medic and crabgrass in days.
This is the middle-ground pick that balances speed, volume, and residual protection. The active ingredient is Quinclorac at 18.92% — the same concentration as the Pro Killer below — but in a 64-fluid-ounce bottle that covers 1,000 square feet per treatment. Customers note it “killed heavy crabgrass in 2 days, yard looked dead in 2 weeks” with no damage to the actual grass, though one reviewer noted it was ineffective on clover. The 30-day residual control (the herbicide stays active in the soil to prevent new weeds from germinating) means fewer repeat applications compared to the Pro Killer’s shorter window.
Compared to the TZone SE gallon jug above, the Drive XLR8 holds half the liquid (64 fl oz vs 128 fl oz), but it uses a water-based formulation that reviewers point out delivers faster plant uptake — a real advantage if you want to see dead black medic quickly. The 4.2 out of 5 star rating from 226 reviews is solid, though the lower score versus TZone’s 4.7 likely reflects a handful of users who saw poor results (one buyer mentioned only 10% weed kill after two weeks). One owner said “I sprayed my lawn with XLR8 and 4 days later, ALL the crabgrass and broadleaf weeds started dying.”
What stands out
- Fast visible results: 2 days for heavy weeds, complete kill in 2 weeks
- 30-day residual control reduces reapplication
- Rainfast in under 1 hour — spray and don’t worry about rain rinsing it off
What to watch for
- Not effective on clover (per one verified review)
- Some buyers reported only 10% weed kill after 2 weeks
- Covers only 1,000 sq ft — far less than TZone’s gallon (16,000 sq ft)
Best for mid-size lawns: If you have 1,000–4,000 square feet of turf and you want the fastest knockdown with month-long residual control, this is the most reliable choice.
Look elsewhere if: Your yard is large (over 4,000 sq ft) — you would need multiple bottles, which pushes the cost above the TZone SE gallon.
2. PBI / Gordon TZone SE Broadleaf Herbicide
The gallon-sized jug that lawn professionals reach for first.
If you have a larger yard (over 4,000 square feet) or you face a mix of tough broadleaf weeds beyond just black medic, this bottle covers the most ground in one pour. The TZone SE label specifically names black medic, wild violet, and ground ivy — three of the most stubborn weeds in a cool-season lawn. At 128 fluid ounces (1 gallon), you can treat up to 16,000 square feet, roughly three-quarters of an average residential lot. Buyers report it works “great” and call it “this is the stuff the pro’s use,” though several warn it is a very strong product that needs careful handling. The trade-off is the upfront cost — it is the most expensive option here, and the full gallon is overkill for a tiny patch.
Owners mention that it “Kills all the weeds and quickly,” matching the 4.7 out of 5 star rating from 125 customers — the highest buyer satisfaction of all three picks.
The big-picture advantage
- Biggest coverage: Up to 16,000 square feet per gallon
- Highest buyer satisfaction: 4.7 / 5 stars from 125 ratings
- Labeled for black medic, wild violet, and ground ivy
The honest trade-off
- Highest upfront cost among the three picks
- Strong formula — requires careful mixing and PPE (personal protective equipment like gloves and long sleeves)
- Overkill for very small lawns or spot treatments
Best for large lawns: If you have over 4,000 square feet of turf and want one bottle that handles black medic plus other broadleaf weeds, this gallon jug delivers the most value per treatment.
skip it if: You only need spot treatment for a small patch — the 64-ounce BASF or 16-ounce Pro concentrate will cost less and waste less product.
3. Pro Crabgrass & Grassy Weed Killer (Liquid Harvest)
A small, potent bottle that matches the pros’ active ingredient at a lower price.
If your black medic problem covers just a patch or two, this 16-fluid-ounce concentrate gives you the same Quinclorac concentration (18.92%) as the BASF Drive XLR8 and TZone SE for the lowest upfront cost. The label lists black medic specifically among the broadleaf weeds it controls. However, the volume is 4 times smaller than the BASF — you get just 16 fluid ounces compared to 64 fluid ounces — so you will need to decide how many treatments your lawn actually needs. Buyers warn that it “kills crabgrass effectively but takes ~6 days for visible results; patience required, not immediate.” That is slower than the BASF’s reported 2-day knockdown, and several reviews mention needing to add a surfactant (a sticking agent) to get the product to cling to plant leaves.
The 4.1 out of 5 star rating from 191 reviews is respectable, but some buyers reported leaking bottles during shipping and that skipping the surfactant resulted in “little to no results” after two applications. Unlike the BASF, this bottle has no stated rainfast window, so you need to plan for 24 hours of dry weather after spraying to prevent wash-off.
One reviewer summed it up: “Mix it right, give it time and it works.”
What you get for the lower cost
- Same 18.92% Quinclorac as premium brands at a budget price
- Explicitly labeled for black medic control
- Small bottle perfect for spot-treating patches
Where it falls short
- 4 times less liquid than the BASF Drive XLR8 — 16 fl oz vs 64 fl oz
- Slower visible results: ~6 days vs 2 days for BASF
- Needs a surfactant to stick to leaves; without it, results are poor
Best for small patches: If you have a lawn under 1,000 square feet or just a few spots of black medic, this is the cheapest way to get the right chemistry without over-buying concentrate.
Not ideal if: You want fast knockdown — the BASF will show results 4 days sooner — or you have a larger lawn, where the 64-ounce BASF or 128-ounce TZone SE will save you from buying multiple bottles.
Understanding the Specs
Active Ingredient Concentration
Quinclorac at 18.92% is the standard for black medic control in post-emergent herbicides (sprays applied after the weed has sprouted). A higher concentration does not automatically mean it is “stronger” — it means you use less product per gallon of water. The 18.92% figure is identical across both the BASF and Pro Killer bottles, so the difference depends on bottle size and additives like surfactants or marking dye.
Residual Control and Rainfastness
Residual control means the herbicide stays active in the soil after application, stopping new weeds from germinating for a set period (up to 30 days on the BASF). Rainfastness (the time you need dry weather after spraying) is short on the BASF — it claims under 1 hour — while the Pro Killer and TZone do not specify a rainfast window, so plan for at least 24 hours of dry weather to be safe.
FAQ
Does Quinclorac kill black medic?
How long does it take for Quinclorac to kill black medic?
Do I need to add a surfactant with Quinclorac?
Can I use these herbicides on a fescue or Bermuda grass lawn?
How much do I need for a 5,000 square foot lawn?
What is the difference between Drive XLR8 and the Pro Killer?
Will these herbicides kill clover too?
Is TZone SE safe around trees and flower beds?
Can I apply these products in the rain?
What is the best time of year to spray for black medic?
Final Thoughts: The Verdict
For most buyers, the herbicide for black medic winner is the BASF Drive XLR8 because it delivers the fastest visible results (2 days), a 30-day residual, and rainfast protection in under an hour — all in a 64-ounce bottle that fits a typical mid-size lawn. If you have a large yard (over 4,000 sq ft), grab the PBI / Gordon TZone SE for the best coverage per gallon. And for small spot treatments or budget-conscious buyers, the Pro Crabgrass Killer gives you the same Quinclorac chemistry at the lowest upfront cost.
How We Picked
We do not accept paid placement. Every pick is matched to a real buyer and a real use-case; we do not hands-on test units.
Sources & Methodology
Specifications: manufacturer listings and product documentation. Review insights: verified customer reviews, as of July 2026. Pricing: not shown on this page (it changes often); check the current price via the retailer link.
As an Amazon Associate, Lawn Gear Lab earns from qualifying purchases. This does not affect which products we feature.