No, putting store bought weed killer in a pressure washer aerosolizes the chemicals responsible for killing plants, causing a health hazard for humans in the process. But is there another way to utilize your pressure washer to kill weeds?
- Herbicide in a Pressure Washer
Herbicide in a Pressure Washer
If you have a weed problem, it may be tempting to load herbicide in a pressure washer and go to town on that crabgrass.
But putting 3000 Pounds per Square Inch (PSI) of pressure behind a tank of synthetic herbicide like Roundup, is not a recommended method of ridding your yard of unwanted plants.
Why? Because most lab made herbicides, especially those that contain Glysophate (the weed killing agent in Roundup) are a health hazard when they become airborne.
When you spray liquid out of a high PSI pressure washer, a significant amount of that liquid become aerosolized. That’s not good for human lungs, both yours and your neighbors’.
That’s why the best way to apply synthetic herbicide is with a hand pump spray with a less than 100 PSI output.
If you don’t have a big yard just need a basic sprayer to spot treat weeds as they pop up, this is all you need:
So, What Kind of Herbicide Can You Put in Your Pressure Washer?
Would we let you leave disappointed? We know your itching to load that liquid blasting machine up with something.
The good news is that there is an herbicide that is not harmful to humans or your pressure washer if used properly.
Turns out the right ratio of white vinegar, salt and liquid dish soap is abhorrent to most common weeds. And, unlike Roundup, it’s an eco-friendly concoction you can safely make at home. And it’s organic!
Here’s a recipe for a homemade, eco-friendly herbicide you can use in your pressure washer. Links are embedded in case you need to buy them:
The soap will help the salt & vinegar mixture to adhere to the weeds for longer, causing sustained damage to the cells in the plant.
How to Use Salt, Vinegar & Soap in a Pressure Washer
Once you have the above solution mixed, put it into the detergent tank of your pressure washer. Next, connect your garden hose to your pressure washer. Set your pressure washer to the detergent or soap spray setting and spray down the unwanted weeds with your pressure washer.
Acetic Acid as an Herbicide
Acetic acid is considered an organic herbicide, and can help you control weed growth in your yard.
Note that the acid level in the vinegar in this recipe is 5%. Many organic gardeners see that a 5% solution is working, but aren’t quite satisfied with the results, choosing to try subsequently with a stronger vinegar.
It’s not recommended to spray vinegar containing more than 5% acetic acid, especially with a pressure washer.
Acetic acid greater than 8% in a solution can cause eye and skin irritation upon contact. Be sure you stick with the 5% acetic acid vinegar for pressure washer use.
Even with the 5% acetic acid solution, avoid direct human contact with the spray out of the pressure washer. This could result in some minor irritation, especially to the eyes, but is considered safe.
Never spray anything out of a pressure washer at close proximity to human skin. The pressure alone can damage skin tissue.
Effectiveness of Vinegar & Salt as an Herbicide
A pressure washer will help you give those weeds a healthy dose of vinegar solution so it may be more effective than a hand pump.
Even so, it likely won’t give you quite the same results as a lab made weedkiller like Roundup.
The vinegar solution is most effective at killing very young weeds and certain broadleaf weeds. Grasses and other weeds with strong root systems may only experience temporary negative effects from a vinegar based herbicide.
Using the vinegar based herbicide in a pressure washer will help you apply more dense and frequent applications, which have been shown to produce better results.
However, there may be some instances with large and deep rooted weeds where hand weeding will be the best way to organically control your unwanted plants.
Effects of Vinegar & Salt Herbicide in a Pressure Washer
A salt & vinegar solution will not harm the steel parts in a pressure washer, but it could possibly be corrosive to aluminum & copper if exposed for a long period of time.
There’s a chance your pressure washer is comprised of steel parts only.
But just to be safe, its recommended that you rinse your machine out with some tap water when you’re done spraying your salt & vinegar solution on your plants.
It a good opportunity to fill your pressure washer tank with water and give your sidewalk a nice cleaning!
Hydro-tilling
With a process that’s come to be known as hydro-tilling, those with dense weed problems have utilized a pressure washer to help remove their unwanted plants.
Hydro-tilling utilizes a high PSI pressure washer (usually gas powered) spayed about 6 inches away from the weeds, disrupting the plants roots system while lifting the plants out of the ground.
One of the main criticisms of hydro-tilling is that while you do temporarily remove the plants, you are still watering weeds, and potentially spreading seeds, encouraging future growth.
However, one can reduce the possibility of enriching the soil for the weeds by following the instructions above, adding salt & vinegar to the detergent tank while hydro-tilling.
You can see how effective hydro-tilling can be in the video below:
Pressure Washing Patio & Driveway Weeds
All home owners know how pesky weeds can be. They seem to find every crack & crevice in a concrete patio or driveway and grow up through them. When you’re cleaning these surfaces with your pressure washer, you might be tempted to blast them with it, but should you?
You should not remove weeds with a pressure washer in between slabs on a patio. The is often compound or sand between the bricks or slabs, necessary to maintain the integrity of the surface, that could be removed with a pressure washer.
Use your best judgement. If, for instance, there are natural cracks that have opened on a smooth driveway or patio surface and weeds are growing up out of them, it’s ok to blast those with the pressure washer.
If you’re unsure, it’s probably best to spray them from a distance of 18 or more inches with a salt & vinegar solution as described above.
Herbicide in a pressure washer: The Verdict
A salt & vinegar solution is the only herbicide that is environmentally safe to put in a pressure washer.
If you have a serious weed problem, you’ll either need to hand pick your weeds or use a lab made herbicide like Roundup that will be more effective on mature and deep rooted weeds.
However, due to the health hazard it creates, you should not put a synthetic herbicide in a pressure washer, which aerosolizes liquid at a PSI output.
If you have a big yard and want to apply a large amount of potent glyphosate based herbicide, consider a large pump sprayer that straps to your back like this one:
