Roundup Not Working (a Guide on Removing Weeds)

Weeds are notorious to get rid of. However, it’s surprising when your herbicide fails to carry out its purpose in life.

So, why is your roundup not working?

Possibly because you didn’t apply it correctly. Other factors such as the type of weeds and environmental conditions play a role. Different types of roundup herbicides have to be applied differently. So this might affect how efficiently your roundup is working.

Surely this is a bit of an oversimplification. Don’t worry, we’ll get to the grimy details. So read along!

Why Does Roundup Not Work?

roundup not working

The Roundup Herbicide works by being absorbed into the plant throughout the leaves. The poison then moves towards the roots to finish the weed. So there can be quite a few reasons for your roundup to not work properly. Let’s take a look at those-

1. Types Of Plants

Some types of weeds are harder to kill than others. Flowering weeds are especially hard to kill. They should be killed before they flower.

However, plants like Marestails are completely immune to Roundup products. These fuzzy-bushed cretins are hard to get rid of. 


The most effective way to kill Flowering weeds is to use concentrated Roundup solutions. 

For normal weeds, use 2 oz of roundup per gallon of water. With plants that have brush and vines, 5-9 oz per gallon of water should be used.

You could use our recommended cups to measure out the amount of Roundup-

For Marestails, the best you can do is rip it out of the ground. Make sure to get the root off completely, so it cannot spread its seeds.

2. Environmental Factors

Environmental factors such as wind and rain can affect roundup’s effectiveness. Rain is responsible for washing away the herbicide. 

The wind is another factor as it dries the chemical before it reaches the root. There’s also an optimum temperature for Roundup. It’s between 53-77 degrees Fahrenheit.


Roundup solutions work best when the environment is dry. For the solution to work properly, it has to be absorbed completely.

It takes about 30 minutes for the Roundup spray to dry. For the Roundup gel, it takes around 2 hours to dry. After waiting for these intervals of time, it’s considered safe for pets and people.

Keep an eye on the weather forecast to avoid heavy rain and wind. Also, take note of the temperature of the day to get maximum effectiveness. Picking the perfect day will ensure the roundup works properly.

If you don’t trust your weather update, use our thermometers to measure it yourself-

3. Sunlight

Sunlight is another important factor. This is because the plant needs sunlight for transpiration. 

An active transpiring plant would die quicker than an inactive one. This is because the poison would reach faster down to the roots.


To ensure proper absorption of the poison, never apply at night. Plants do not photosynthesize then.

Apply in the morning where the temperature is mild. Avoid applying when the sun is harsh and hot. Plants don’t photosynthesize when the sun’s too bright.

A key indicator that your weedkiller is working is to check-in after 6 hours. If the poison takes effect, the plant will start to wilt and brown.

Other than these environmental factors, the rest is on how you apply them. Proper application of the weeds ensures effective culling.

How to Properly Apply Roundup?-Precision Vs Range

There are different applications for different sorts of landscapes. Roundup is a non-selective weedkiller. In layman’s terms, it kills everything it touches. 

This is why you have chosen between wide area coverage and precision control. Hardscapes such as patios and driveways require a wide area coverage. This is because you wanna get every crack coated.

However, for soft scapes like gardens and lawns, precision control is advised. You want to protect the plants you keep.

As you’re handling hazardous chemicals, it’s wise to wear rubber gloves for protection. 

If you’re unsure about which of these gloves to invest in, take a look at our picks below-

Now that you’re protected, let’s get to the specifics.

1. Precision Control

For precision control, you could use Roundhouse Gel and the attachments with the spray. These target specific weeds while protecting the surrounding plants.

Trigger Sprayer

With the trigger sprayer, all it takes is one spray. One spray kills one weed. You have to get close to the plant to spray it.

Comfort Wand

The comfort wand allows you to go easy on your hands. One press of the button sprays the necessary amount to kill a weed.

With this, you don’t have to constantly squeeze the trigger.

Sure-shot Wand with Shield 

The sure-shot collapsible wand and shield cap ensures precise dispensation. The plastic shield protects the surrounding plants and only allows you to kill the weed.


For the proper application of the roundup gel, give the tab one click. It will only dispense the amount you need.

Dab the leaves of your weed with the gel. You only have to apply once to kill the weed. Don’t apply twice.

2. Wide-Area Coverage

This is particularly for hardscapes with concrete and gravel. Weeds are notoriously resilient. 

They can emerge out of the tiniest cracks. You have to ensure to spray wide areas to get all the cracks

Roundup Pump and Go Weed Sprayer

The Pump and go sprayer allows you to pump for 10 minutes at a time. All you have to do is pump it 3-4 times to pressurize the herbicide.

Next, pull the wand out till it clicks and starts spraying. This is perfect for covering large areas.

In conclusion, this is why your roundup isn’t working and how to properly apply it. Ensuring proper application would allow you to kill weeds effectively.

Frequently Asked Questions

Question: How many days do I have to plant again after using Roundup?

Answer: You can safely plant shrubs, trees, and ornamental flowers the day later. 3 days is the time required before planting edible trees and shrubs.

Question: Should I mow before using Roundup?

Answer: Never mow before using roundup. Roundup Herbicides require leaves to be absorbed through.

Question: At what temperature do weeds struggle to grow?

Answer: Anything below 55 degrees Fahrenheit. If it’s below this level the weeds will remain dormant.

Bottom Line

Now you know how to deal with your problem regarding your roundup not working. Hopefully, our solutions helped you acquire maximum effectiveness. 

Let us know if you could make it work. Till then, stay safe and say no to weeds!

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