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How Long Does 2, 4-D Take To Work?

Quick Answer: On average, it takes about 10-20 days for 2, 4-D to take effect.

Are you using 2, 4-D weed killer in your yard?

If you are using 2, 4-D or thinking about it, you are among many lawn care people who are. However, like many others who use this product, you may not fully understand the chemical you are using and how it works.

So, let’s talk science for a second…

The 2, 4-D chemical, weed killing machine you are so familiar with, in scientific terms, is actually an organic compound called 2,4-Dichlorophenoxyacetic acid or (2, 4-D Dichlorophenoxy) acetic acid. An organic compound is merely a chemical compound that has carbon in its chemical structure.

Though this is an organic compound, 2, 4-D is not a naturally occurring chemical. This just means that humans had to have their hands in it for this chemical to come about.

Since being introduced in 1945, 2, 4-D has been one of the most widely available herbicides. After other companies could start adding 2, 4-D to their products, it has become a main acting ingredient in thousands of herbicides.

Okay, that’s enough science, for now, …let’s talk the basics…

What is a Herbicide?

Herbicides, i.e., weed killers, are chemical substances created with one of two primary goals in mind; either it is a selective herbicide, or it is a non-selective herbicide.

Selective Herbicides 

Kills only “select” undesired weeds.

Non-Selective Herbicides (Total Ground Killer)

Kills any plant it touches – grass, flowers, weeds, etc.

What is “Persistence”?

Persistence, also called residual action, is a chemical’s ability to stay around and do its job. Meaning that an herbicide with a greater persistence will have more of an impact because it will remain on a plant longer.

What is “Means of Uptake”? 

Means of uptake essentially talks about how a plant absorbs a chemical.

When applying a herbicide, you need to know where a plant absorbs it for it to be effective. Is it absorbed through the roots, leaves, or some other way?

Last But Not Least, What is The “Mechanism of Action”?

The mechanism of action is how a herbicide works.

So, how does 2, 4-D fit into these basics:

  • 2, 4-D is a selective herbicide
  • It has a high persistence.
  • It has various means of uptake because it is present in many widely used herbicides in the lawn care industry, though it is typically absorbed through the leaves.

Now that we know some basics let’s discuss the mechanism of action of 2, 4-D – how it works.

To truly be able to explain how 2, 4-D works, we will have to talk some science again.

2, 4-D is a synthetic auxin. Auxins, simply defined, are plant hormones that coordinate plant growth, development, and behavior. When 2, 4-D comes in contact with a plant, mainly broadleaf weeds (aquatic and terrestrial), it changes how a plant works.

Basically, 2, 4-D goes undercover inside a plant and starts giving new orders on how things should be run.

This auxin takeover means 2, 4-D is running the show and telling the plant how it should grow. Instead of doing what you’d think, 2, 4-D doesn’t tell the plant to stop development, on the contrary, this synthetic auxin tells the plant cells to grow, grow, and grow some more.

It makes the vascular cells of a plant (the cells that carry water and nutrients) kick it into overdrive. This high gear of nutrient and water passage forces the plant to grow out of control, which results in plant death.

In summary, 2, 4-D is an effective herbicide ingredient because it changes the way a plant grows which causes it to die.

As fascinating as the superficial, interworkings of this chemical are, you probably just want to know how long it takes for it to work.

On average, it takes about 10-20 days for 2, 4-D to take effect.

You have to keep in mind that the way this herbicide works is reliant on how quickly a plant can overgrow and die. Some plants, even when forced to grow quickly, will still grow rather slowly.

Growth in a plant, even when given orders to grow quickly, can only grow so fast. Their growth is reliant on the amount of nutrients, sunlight, amount of water, and more available to them.

If you want 2, 4-D weed killer to work faster, you can always apply a surfactant.

A surfactant, in this case, is a compound that changes the surface properties of a plant and allows liquids to adhere more easily. Essentially, a surfactant will cause liquids like 2, 4-D to stay on a leaf and not roll off onto the ground. Since 2, 4-D is absorbed through leaves, using it with a surfactant that keeps the chemical on the leaves will help it work faster.

Side Note: If you are considering or currently using 2, 4-D to kill the weeds in your lawn, please do your research first. Know what you’re using before you use it!

About the author

    Matt Hagens

    Hi, I'm Matt the owner of Yard Care Gurus. 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. Thanks for stopping by!

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