How Long Does Gordons Liquid Trimec Take to Kill Weeds?

We all should be very grateful for the advances in modern weeding techniques. The chemicals now available allow the backbreaking labors of our youth to be push-of-a-button exercises in adulthood.

That being said, we can all get a little impatient waiting for the chemicals to take effect.  This article will help you know how long your Trimec liquid weed killer will take to become effective.

What is Trimec Liquid Weed Killer?

Trimec Liquid Weed Killer is a concentrated chemical that kills 250+ broadleaf weeds and will not harm lawn when applied correctly.

Which weeds does Gordon’s Trimec kill?

Gordon’s Trimec boasts to control over 250 different types of broadleaf weeds. It is particularly effective against hard-to-kill weeds such as:

  • Dock
  • Ground Ivy
  • Healall
  • Lespedeza
  • Mallow
  • Morningglory
  • Oxalis
  • Pigweed
  • Poison Ivy
  • Poison Oak
  • Sheep Sorrell
  • Speedwell
  • Spurge
  • Virginia Buttonweed
  • Wild Carrot
  • Wild Onion
  • Yarrow

In addition to hard-to-kill weeds, Trimec also controls most sensitive weeds such as:

  • Dandelions
  • Clover
  • Chickweed
  • Bedstraw
  • Black medic
  • Buckhorn
  • Knotweed
  • Lambsquarters
  • Peppergrass
  • Plantain
  • Purslane
  • Ragweed
  • Shepherdspurse
  • Wild lettuce

Here are just a few others that it controls:

  • Aster
  • Black-eyed Susan
  • Falseflax
  • Poison Ivy
  • Poison Oak
  • Catnip
  • Scarlet Pimpernel
  • Hawkweed
  • Jimsonweed
  • Spiny amaranth
  • Russian thistle
  • Spurweed
  • Stinging nettle
  • Mallow
  • Matchweed

For a full list, please see the Gordons Trimec PDF instructions here.

How to I apply Trimec to my Lawn?

Trimec is applied via a sprayer. Proper amounts, timing, and ratios of product to water for almost all situations can be found in the user guide.

How much Trimec should I put in a gallon of water to spray?

While there are many different factors to consider (what type of sprayer, northern vs. southern lawn), the general rule is to use 1 to 1.5 oz per gallon of water per 1000 sq/ft of turf.

What temperature should I spray at?

In order for Trimec to be effective, it’s important that it be applied when the temperature is between 65 and 80 Fahrenheit. Spring and fall are the recommended best times for application.

How long does Trimec take to kills weeds?

According to Gordon’s website, the product should begin to work within 4-6 hours of application but will take 2-4 weeks depending on plant age and health. This holds true for most weeds. Trimec will kill both dandelion and clover in about two weeks.

How long should I wait to re-apply?

You may be thinking, “I can’t tell if I see results. How long after the first application can I re-apply?” Remember, over-applying any type of weed killer can cause harm to the lawn, such as scorched yellow patches and other problems (I know it did for me when I was too trigger happy).

Wait 30 days minimum after application to re-apply. The maximum number of broadcast applications is twice a year, with spring and fall being the optimal times to apply.

How long should I wait to mow after spraying times?

It’s best to mow either two days before or two days after application.

How long does Trimec take to dry?

Trimec will generally dry within 4-6 hours of application.

How long before I can walk on my grass again?

Once the grass is dry (between 4-6 hours), you will be fine to walk on it again.

What about rainfall and sprinklers?

It is recommended that you apply Gordon’s Trimec on a day when you don’t expect rain, as it will need 24 hours without rainfall or irrigation to be effective.

Northern vs. Southern Lawn

Gordons Trimec is safe and effective to use on both Northern and Southern Lawns.


Author: Matt Hagens

Hi, I’m Matt the owner of Obsessed Lawn. I love to be outside working on my lawn, planning my next project. I created this website to help people like you find the best products for yard care and great advice. Learn more about me and find me on Facebook.