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Trimec Mixing Calculator: Oz Per Gallon by Turf Type

Trimec combines three actives — 2,4-D, MCPP (mecoprop), and dicamba — in a three-way blend that's been the standard broadleaf lawn herbicide for decades. What trips people up is that "Trimec" isn't one formula: it's a licensed name used across several products at different concentrations. This page covers the widely available consumer Trimec Lawn Weed Killer, the one most homeowners actually have.

Quick facts: 2,4-D + MCPP + dicamba three-way blend · rate set by turf type, not weed type · never use on "Floratam" St. Augustine · wait 30 days between applications.

Need a broader broadleaf tool instead? 2,4-D Mixing Calculator · Pasture brush job? Crossbow Mixing Calculator

Calculator

Trimec Calculator — By Turf Type

Pick your turf type, enter the area, get product and water needed.

"Trimec" is a family, not a single product

PBI/Gordon's licenses the Trimec formula across a whole product line, and each one carries a genuinely different active-ingredient percentage and rate table:

If a rate you found online doesn't match what the calculator above gives you, this is almost always why — check which specific Trimec product is on your label before assuming a number is wrong.

What Trimec controls — and where it can't go

Trimec's three-way blend controls over 200 broadleaf weeds — dandelion, clover, chickweed, plantain, ground ivy, and more — while established grass at label rates keeps standing. It won't touch grassy weeds like crabgrass or nutsedge; those need a different, grass-targeted herbicide entirely.

FAQ

How much Trimec do I mix per gallon of water?

For Gordon's Trimec Lawn Weed Killer, the standard rate is 4 fl oz per gallon of water per 1,000 sq ft for most turf types (bahia, bermuda, fescue, Kentucky bluegrass, perennial ryegrass, zoysia), dropping to 2 fl oz per gallon per 1,000 sq ft for centipede and St. Augustine, which are more sensitive to 2,4-D. Other Trimec products (Trimec 992, Trimec Classic, Trimec Southern) use different concentrations and different rates — check which one you actually have.

Why do different Trimec rates show up online?

Because Trimec isn't one product — it's a licensed formula sold under several names at different concentrations: the widely available consumer Lawn Weed Killer, Trimec Southern (lower 2,4-D for sensitive warm-season grass), and professional-grade Trimec Classic and Trimec 992. Each carries its own rate table. A rate you saw for one doesn't transfer to another.

Can I use Trimec on St. Augustine or centipede grass?

Only at the reduced rate, and never on "Floratam" St. Augustine specifically — it's not tolerant of 2,4-D at any rate. For St. Augustine and centipede generally, Trimec Southern's lower-concentration formula is the safer purpose-built choice over the standard consumer product.

How long between Trimec applications?

Wait a minimum of 30 days between applications, and don't exceed 2 broadcast applications per year on the same site. Delay mowing 1 to 3 days before and after applying so the leaf surface can fully absorb the herbicide.

What weeds does Trimec control?

Over 200 broadleaf weeds, including dandelion, clover, chickweed, plantain, and ground ivy, while leaving established grass unharmed when used at label rates. It won't touch grassy weeds like crabgrass — that needs a separate pre-emergent or grass-specific herbicide.

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Important note

Rates here reflect the consumer Trimec Lawn Weed Killer label; the current product label on your specific bottle is the legal document and its turf-type table, use sites, and precautions govern. Wear label-required PPE including chemical-resistant gloves↗ when measuring and mixing. Affiliate links support the site at no extra cost to you.