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 but 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, but now I know, I thought I’d share my knowledge with all you like-minded lawn-lovers out there.

Best Time To Apply 2-4-D Herbicide

I have found, after much trial and error, that the best time to apply 2-4-D-based herbicides is in spring and in 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 too.

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

Best Time Of Year To Apply 2-4-D

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

Firstly, annual winter weeds begin their lifecycle in late summer. The process of germination takes place in fall and during winter before the active growing season commences in spring. So, administering weed herbicide at the beginning of the germination period is a good way of controlling and preventing their lifecycle in its tracks before full growth commences the following spring.

Another reason for advocating that fall is 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 is 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, at any time and not just in the fall.

Therefore, 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

Best Time Of Day To Apply 2-4-D

Mid to late morning when the dew on your lawn or pasture has evaporated is the best time of day to apply 2-4-D weed killer. This applies whether you are 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 with 48 hours of applying. If applied in conjunction with a surfactant it will be at its most effective.

The effectiveness of 2-4-D is dependant 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 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 an early morning, evening time, and late morning through to the late afternoon.

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 you having 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 also is prevented from penetrating or being absorbed by weeds if any residual water is left on foliage because this acts as a waterproof barrier.

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

How Long After Spraying 2-4-D Can I 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 2-3 days prior to spraying. This is to ensure there is plenty of leaf surface for the chemical to land on as you spray.

All decent herbicides containing 2-4-D will come with manufacturer recommendations on how long 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 just a light shower within those first 24 hours after applying 2-4-D will dilute the formula and significantly decrease its effectiveness. It is simply a waste of time, money, 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 Pasture

Spray 2-4-D on pasture in spring and in the 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 quickly 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 in their tracks. 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 that is not forecasted any rain for the following 24 hours and has 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 so ideally, the weather needs to have been dry for a few days previous to spraying.

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

For best results and less chance of having to reapply, avoid an early morning, evening time, and late morning through to the late afternoon.

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

The herbicide 2-4-D is not considered to be a risk to grazing cattle according to The National Library of Medicine. The only caveat to this opinion is in relation to lactating dairy cattle where a report from The Texas A&M University System advises against these animals grazing on 2-4-D treated pasture for at least 7 days after being sprayed.

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

Frequently Asked Questions