2-4-D is a fantastic choice for treating weeds on our lawns, but what is the best time to apply it?
You may have applied 2-4-D with little to no success, or you’re tackling your first lawn treatment with the herbicide.
Either way, we’ll help you get the ultimate results.
There is an optimal time to apply 2-4-d for ultimate results, and we’ll help you determine it.
The best time to apply 2-4-D for ultimate results is dependent on temperature, rainfall, mowing, and season. Overall, most lawn enthusiasts agree the most effective applications are applied to lawns mid-morning during the fall a few days after mowing when the grass is dry.
You’re likely wondering why these factors matter so much when applying 2,4-D weed killer.
Timing is everything as far as the effectiveness and potency of the herbicide go.
We’ll share all our knowledge on how 2-4-D works and how to get the ultimate results from your applications.
Table of Contents
When Is The Best Time To Apply 2-4-D?
Walking outside to find a new invasion of pesky weeds is a frustrating situation for homeowners attempting to foster a healthy, beautiful lawn.
Luckily, there are many herbicides and weed killers on the market capable of dealing with pesky weeds.
2-4-D is one of the most popular types of herbicides celebrated for its effectiveness at keeping weeds at bay without harming our beloved green grass.
However, improper application drastically reduces the effectiveness and potency of 2-4-D herbicides.
Seasoned lawn care enthusiasts apply 2-4-D twice a year to kill off unwanted weeds taking residency on their beautiful lush lawns.
Since we want to make two separate applications each year, picking the best seasons to treat our lawns is advantageous.
Because of the extreme temperatures possible in summer and winter, 2-4-D tends to be more effective in the spring and fall, where temperatures stay more moderate.
2-4-D works best between 60-85° degrees Fahrenheit (29° C) when weeds are at their most prolific growth stages.
During prolific growth stages, weeds actively grow the leaves necessary for 2-4-D to work.
Applying the herbicide at this time allows for more surface area for the 2-4-D to adhere to and subsequently absorbed into the unwanted weeds.
While there is some debate among lawn care enthusiasts, fall is generally considered the best time to apply 2-4-D.
Still, many distribute another application in the spring to get ahead of the weeds once the growing season starts again.
Time of day is another important aspect to consider in applying 2-4-D.
High temperatures and sun evaporate the solution and drastically reduce its effectiveness.
You’ll want to make sure you apply before the strongest heat of the day to prevent evaporation.
Rainfall also influences the potency differently.
Rain washes away the solution before it has had time to be absorbed into the plant.
Be careful after rains when water still exists on the blades of grass.
The water on the leaves will reduce the potency and drastically decrease its effectiveness against pesky weeds.
What Is 2-4-D?
This article may help a bit more by understanding exactly what 2-4-D herbicide is.
The “D” in 2-4-D stands for Dichlorophenoxyacetic acid, which is a systemic herbicide particularly effective against broadleaf leaves.
One of the most alluring aspects of 2-4-D is its ability to eradicate unwanted weeds without negatively impacting grass.
We all know lawn care is a labor of love, and getting the desired results often takes some work and special techniques.
I’m sure we’d all hate for our hard work to be undone through damage from an herbicide.
This is why 2-4-D is so popular among lawn care enthusiasts.
For more info on this weed killer, check out our guide for how many ounces of water to mix with 2-4-D.
How Does 2-4-D Work?
2-4-D is an auxin-type herbicide. It works by adhering to the broad leaves of unwanted weeds.
The leaves absorb the herbicide solution the same way they absorb water.
Once absorbed into the leaves, the 2-4-D solution is carried into the roots, where the real work is done.
The 2-4-D causes uncontrolled growth of cells within the plant, which ultimately kills them off.
These weed herbicides alter the plant’s growth system and cause endless growth of the cells responsible for transporting water and nutrients to the rest of the plant.
Once the growth cycle is altered, the plant cannot grow correctly and ultimately dies off.
The absorption process makes it great for eradicating broadleaf weeds from our hard-earned lawns.
What Does 2-4-D Herbicide Kill?
We’ve established how 2-4-D works and kills grass weeds, but what exactly does it kill off?
Lucky for us, it kills many of the pesky unwanted weeds we find popping up in our lawn.
2-4-D is a selective weed killer.
Selective herbicides target specific types of plants without harming others.
Most grass varieties are not harmed by 2-4-D, but we recommend you ensure your grass will not be damaged.
We particularly recommend this for those with turf-type grasses on their lawns.
2-4-D kills well over 100 different types of weeds.
Some of the most common unwanted weeds the herbicide kills include:
2-4-D Does Not Kill Crabgrass
One major weed responsible for many headaches among lawn care enthusiasts is crabgrass.
Unfortunately, since crabgrass is a type of grass, the 2-4-D herbicide effectively kills it and other grassy weeds.
You’ll need to look for a herbicide specifically formulated for crabgrass.
This particular weed killer is very effective against killing off unwanted crabgrass.
Many herbicides effective against crabgrass are non-selective and kill any plant it touches.
While they are great for eradicating tough weeds, they are also harmful to grass.
Because of this, we recommend making spot application of the crabgrass so as not to negatively impact the rest of your grass.
Another helpful tip for crabgrass is to overseed once the herbicide application is complete.
Overseeding allows grass to establish itself over patches and limit space for unwanted weeds to pop up.
Factors To Consider When Applying 2-4-D
Since we know the effectiveness of 2-4-D herbicide in treating unwanted weeds on lawns, we want to ensure we are getting the most out of our applications.
Improper application wastes product, time, and energy, so let’s make sure we set the 2-4-D up for success.
Lawn care often requires labor and investment in products.
This is why getting it right the first time is so important to not waste any money, energy, or time.
If you are a “do it yourself” type of person, you’re likely well aware of the frustrations of trial and error.
There are a few important factors to consider when applying herbicide.
Setting yourself up for success drastically reduces the amount of frustration and head-scratching when it comes time to treat our lawns for weeds.
Temperature Affects effectiveness of 2-4-D
The 2-4-D herbicide tends to work best in certain temperatures.
High temperatures tend to evaporate the solution before it has had ample time to be absorbed into the leaves and low temperatures reduce the efficacy of the herbicide.
Because of this, it is best to make sure temperatures stay under 90° degrees Fahrenheit (32° C) and above 65° degrees Fahrenheit (18° C) to make sure the 2-4-D gives you optimal results.
Temperature plays a significant role in the growth of weeds.
Warmer temperatures allow all plants to grow, including pesky weeds.
The best time to apply 2-4-D for ultimate results is when the unwanted weeds are actively growing or young.
While you don’t want evaporation from excessively high temperatures, you want warm temperatures for weeds to actively grow for optimal results.
Time Of Year Is Important
The time of year is very important when applying 2-4-D.
The best times of year are spring and fall.
The moderate temperatures during these seasons allow the herbicide to work best.
Another reason these seasons work well is their correlation to the growth cycle of many broadleaf weeds.
Since the 2-4-D needs to adhere to the leaves of the unwanted weeds, it helps to have decent growth for the solution to stick to.
Most lawn enthusiasts prefer fall applications to kill weeds, but many also add another application during the spring.
Two applications of 2-4-D a year will get the ultimate results and give you the best chance at eradicating unwanted weeds from your lawn.
It is important to determine its dormancy stage if you have Bermuda grass.
Some 2-4-D weed killers can damage lawns by killing Bermuda grass in its dormant stage.
Grass tends to be more vulnerable in its dormancy stage, and Bermuda grass is particularly susceptible to damage from poorly timed 2-4-D applications.
Bermuda grass tends to enter the dormant stage in January.
You might want to check out our post on weed killers that won’t harm Bermuda grass for a list of options.
Time Of Day For Ultimate Results
Lawn care enthusiasts experience different results from 2-4-D based on the time of day it’s applied.
Applying too early in the day does not allow enough time for dew to dry, which dilutes the herbicide solution.
If you wait too long, the afternoon sun contributes to high temperatures capable of evaporating the 2-4-D solution before it’s absorbed into the weeds.
We recommend a mid-morning application once the dew has dried for ultimate results.
If you live in an area with high winds during the daytime, consider a nighttime application to reduce the likelihood of wind carrying off the treatment.
Rainfall Affects Potency Of 2-4-D Application
Rainfall washes away herbicide from plant leaves.
Rain after applications does not give the 2-4-D enough time to sink into the leaves of the pesky weeds.
You’ll want to make sure there is no rain in the forecast 24 hours after application.
Many 2-4-D herbicide products usually indicate 6-8 hours after application before rainfall, but we like to err on the side of caution when it comes to lawns.
It is equally important to allow ample time after rainfall as well.
If water is present on the leaves, it dilutes the herbicide solution and drastically reduces its efficacy.
If the solution is diluted, it won’t be enough to do the job of killing pesky weeds.
Ensure you do not have wet grass before applying the 2-4-D solution to prevent dilution.
Wind Impacts 2-4-D Application
Another often overlooked factor to consider when applying herbicide is wind.
We recommend checking the predicted wind speeds for your area for the day you plan on applying herbicide to make sure it does not blow away.
Winds over 5 mph are strong enough to carry herbicides away from desired areas.
Not only does this remove it from the weeds you are targeting, but it also is possible for it to blow into gardens and kill off flowers and plants you want to keep around.
2-4-D does not only kill weeds.
It also kills plants you may be actively growing in your garden, including:
- Morning Glory
To be safe and err on the side of caution, we recommend only using the 2-4-D herbicide away from crops and gardens.
Even if we check the predicted wind speeds, it is hard to tell when a big gust will come in and transfer the herbicide from weeds to your food crops.
It’s best to be cautious when it comes to food crops and gardens so as not to undo hours of labor and waste money.
Mowing Height For 2-4-D Applications
It is important to make sure you consider mowing in determining the best time to apply 2-4-D.
Most products indicate waiting 2-3 days after applying the herbicide to your lawn before cutting.
It also helps to wait at least 2-3 days after mowing before applying the 2-4-D solution.
Mowing cuts the leaves on weeds and reduces the area present for the solution to adhere.
Since 2-4-D is absorbed through the leaves, you want to ensure enough surface area before application.
How Long Does 2-4-D Take To Kill Unwanted Weeds?
If you’ve put our tips to action and applied the 2-4-D herbicide to your lawn, you’re probably wondering how long it takes before seeing the results of all your hard work.
Usually, it takes about 14 days for the 2-4-D to eliminate existing weeds.
You’ll start to see wilting and withering about 48 hours after application.
The wilting, withering, and yellowing of the weeds is a sure sign your application was successful.
How To Properly Apply 2-4-D Herbicide For Optimal Results
Since we are now well versed in how 2-4-D herbicides work and when to use them, we’re going to give you a few helpful tips and tricks to get you on your way to a weed-free lawn.
Timing is one of the most crucial factors for optimal results from your 2-4-D applications, but other helpful methods exist.
Make Sure The Timing Is Right.
Have you checked the weather for temperature, wind, and rain?
All of these factors dramatically impact the efficacy of 2-4-D herbicides.
Make sure it is a moderate temperature between 65-85° degrees Fahrenheit (29° C), wind speeds are 5 mph or less, the grass is dry from previous rain, and no rainfall is predicted for the next 24 hours.
Also, consider your last mow.
You want weed leaves to have enough surface area to adhere to, so make sure it has been at least 2-3 days since your last mow.
Read All Instructions On 2-4-D Product
Timing will set your herbicide application up for success for ridding your lawn of unwanted weeds, but it won’t do much if you don’t read the instructions on your choice of 2-4-D product.
Make sure your mix ratio is on point.
If the concentration is too high, you may harm your grass. If it is too low, it won’t be strong enough to effectively kill pesky weeds.
Use Quality Sprayers To Apply Herbicide
Fan sprayers like this one help evenly distribute herbicide over large areas like your entire lawn.
They also work well for spot applications to kill specific patches and individual weeds.
Check Back To Make Sure Your Application Was A Success
It takes some time for the 2-4-D herbicides to kill weeds.
The solution has to be absorbed into the leaves and down into the roots to kill unwanted weeds.
Full results usually take 14 days or more, but you’ll start to see weeds dying off just 48 hours after application.