Best Time To Apply 2-4-D Herbicide To Lawn And Pasture

So you’ve heard that 2-4-D is one of the best selective herbicides on the market to rid your lawn or pasture of broadleaf weeds. Now you need to get a handle on when the best time to apply it is.

It’s taken me a while to get on top of controlling the weeds in my lawn and understanding when the best time to apply 2-4-D herbicide is. Now that I know, I thought I’d share my knowledge with all you like-minded lawn-lovers out there as well.

When To Apply 2-4-D Herbicide For The Best Results

I have found, after much trial and error, that the best time to apply 2-4-D-based herbicides is in the spring and the fall. 2-4-D is known to have little impact on killing weeds in summer when the weather is warm because the herbicide tends to evaporate quickly, especially in temperatures over 90 degrees. Likewise, anything lower than 60 degrees will reduce the effectiveness of this weed killer.

Weeds either need to be actively growing or very young for 2-4-D to have the biggest impact and longest-lasting effects. Let me share with you exactly why that is.

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Applying 2-4-D Throughout The Year

If I could only apply 2-4-D weed killer once per year, it would be during the fall. There are a few reasons for this.

First, annual winter weeds begin their life cycle in late summer. The process of germination takes place in fall and winter before the usual active growing season in spring. Administering herbicide at the beginning of the germination period is a good way of controlling and preventing weed life cycles before full growth commences the following spring.

Another reason I advocate for fall as the best time of year to apply 2-4-D is because this is the time when perennial broadleaf weeds are preparing for winter. During this time, they shift energy from their leaves to their roots. The 2-4-D herbicide that is sprayed on the roots of these weeds is quickly absorbed and then carried to the roots faster than at any other time of the year. Boom!

For a belt and braces approach to weed control in my lawn and pasture, I also apply 2-4-D in spring. It is no secret that weeds are notoriously opportunistic plants that seem to just appear in your lawn and pasture from nowhere and at any time (not just in the fall).

I find that applying a second treatment of 2-4-D in spring while the weeds are relatively small also serves to eliminate a bumper crop of pesky annual and biennial broadleaf weeds for the duration of the summer.

Whoever said that taking pride in keeping your lawn in pristine condition and as weed-free as possible wasn’t a labor of love?

You can buy 2-4-D Weed Killer online here at

Applying 2-4-D At Different Times Of The Day

Mid to late morning, after the dew on your lawn or pasture has evaporated, is the best time of day to apply 2-4-D weed killer. This is true whether you’re spot-treating a small area — for example, a small bunch of clover in your lawn — or if you are using it to treat your entire lawn or pasture using a backpack sprayer.

This is because the effectiveness of this herbicide diminishes when it comes in contact with water. It can either become diluted by water or the water can act as a barrier between the foliage of the weed and the chemical, essentially protecting the weed from harm.

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

2-4-D is a slow-release herbicide that typically takes up to 14 days to completely kill the weeds in your lawn. You will begin to notice the first signs of wilting and discolored weeds within 48 hours of applying. It will be most effective when applied with a surfactant.

The effectiveness of 2-4-D is dependent on the weather conditions before, during, and after it was applied. Ideal conditions for application include spraying on a wind-free and dry day. This will ensure that the chemical is absorbed by the offending weeds and that it has a chance to penetrate the roots.

When To Spray 2-4-D On Your Lawn

2-4-D is sensitive to extreme temperatures which can cause it to evaporate quickly when exposed to temperatures of more than 90 degrees Fahrenheit and become less effective in temperatures lower than 60 degrees Fahrenheit.

For this reason, if you want the best results and less chance of having to reapply, avoid applications in the early morning, afternoon, and evening.

You also want to pick a day with little or no wind. Anything more than a wind speed of 5mph will cause the chemical to get blown in all directions.

Can You Spray 2-4-D On Wet Grass?

Spraying 2-4-D on wet grass will significantly reduce its effectiveness and may result in needing to reapply due to unsatisfactory results.

At the risk of repeating myself and as I said a little earlier in this article, 2-4-D tends to become diluted when it comes into contact with water. It’s also prevented from penetrating or being absorbed by weeds if any residual water is left on foliage.

Take it from someone who got caught in a rain shower whilst applying this to my lawn last fall, wait until you have dry conditions to prevent you from having to reapply.  

How Soon After Spraying 2-4-D Can You Mow?

I always wait at least three to four days after spraying 2-4-D before I mow my lawn. This leaves an adequate amount of time for the weeds to absorb the herbicide and for it to be transported to the roots and take hold of the plant.

I also won’t mow my lawn for the 2 to 3 days prior to spraying. This is to ensure there is plenty of leaf surface for the chemical to land on as I spray.

All decent herbicides containing 2-4-D will come with manufacturer recommendations for how soon after spraying you can mow. Make sure you have a good read of the label before you begin spraying.

How Long Does 2-4-D Need To Be On Before Rain?

Timing is everything when you apply 2-4-D. You need to apply this herbicide at least 24 hours before any rain is forecast.

Even a light shower within those first 24 hours will dilute the formula and significantly decrease its effectiveness. It is simply a waste of time, money, and product… not to mention effort!

You’ll be pleased to know that any rain that falls after those first 24 hours will not make much difference in its effectiveness at killing the weeds in your lawn.

When To Spray 2-4-D On Pastures

Spray 2-4-D on pastures in the spring and fall, when weeds are either small or when they are actively growing.  Avoid administering 2-4-D during intense periods of warm weather as it is known to evaporate in temperatures over 90 degrees Fahrenheit.

Applying the correct mixing ratio of 2-4-D in the fall will stop any broadleaf weeds that are beginning to germinate or prepare for winter. Applying a spring application prevents any young, new, and small weeds from fully taking hold in your pasture. A twice per year schedule of applying 2-4-D should suffice, although you may need to undertake a little spot control in between.

To administer 2-4-D in the most effective way and to avoid any need for re-application, you should make sure you choose a day without any rain in the forecast for the following 24 hours and with little or no wind.

You need the pasture to be dry before you start so that the herbicide can be easily absorbed by the weeds. Ideally, the weather needs to have been dry for a few days prior to spraying.

On the day of spraying, wait for any dew to clear before you get underway. Bear in mind that you will need to get the job completed before the mid-day heat sets in to avoid the 2-4-D evaporating.

How Soon After Spraying 2-4-D Can Cattle Graze?

The herbicide 2-4-D is generally not considered to be a risk to grazing cattle. The only caveat to this opinion is in relation to lactating dairy cattle. A report from the Texas A&M University System advises against such animals grazing on 2-4-D-treated pasture for at least 7 days after application.

You can buy 2-4-D Weed Killer online here at

Frequently Asked Questions