Pesticide, herbicide, fungicide–these are just a few purposes dish soap is commonly used for on lawns.
It certainly seems like a more eco-friendly and less costly, safer alternative for getting rid of various pests in your yard, but is it really effective or merely the stuff of urban legends?
Dish soap is somewhat effective as an inexpensive weed killer and pesticide, as it rapidly dehydrates most insects and removes most weeds’ protective oils, especially when used with vinegar. However, it also is very damaging to grass and other plants you likely want to keep around.
If you’re curious about whether or not the dish soap in your kitchen is worth using on your lawn, keep reading as we cover dish soap’s supposed uses, if it’s worth it, and what alternatives you have.
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What Is Dish Soap Used For On Lawns?
Dish soap has been used for various purposes on lawns for decades, mostly as a supposedly less environmentally damaging method of weed and pest control than other harmful chemicals.
With the advent of the internet, the rumors surrounding its efficacy have only grown and spread further.
At some point, you’ve probably seen someone touting Dawn or Palmolive as an excellent means of getting rid of annoying insects, deterring other larger lawn pests, and even killing all manner of harmful weeds and fungi plaguing your yard.
Other proponents of this unusual method claim mixing dish soap with other products like salt or vinegar boost its effectiveness.
However, it’s also worth mentioning liquid dish soap isn’t a particularly selective herbicide or pesticide, meaning it is capable of doing quite a bit of damage to your lawn and other desirable plants you don’t want to get rid of.
After all, most dish soaps on the market contain surfactants.
Surfactants reduce surface tension between two liquids and are often used in cleaning products like detergents, shampoo, and, yes, herbicides and insecticides.
Unfortunately, the surfactants in dish soap are very harsh on lawns and don’t discriminate between grass, weeds, and desirable plants.
Still, dish soap is inexpensive, easily accessible at just about every grocery or convenience shop on the planet, and in a pinch, it’s easy to see why so many homeowners reach for the
Dawn soap when they want to get rid of some pesky bugs or dandelions cropping up on their lawn.
Is Dish Soap Harmful To Grass?
While it isn’t quite as harmful as, say, bleach, you might not want to use liquid soap, whether it’s for dishes or your hands, on weeds near grasses you want to stay healthy and green.
Like we touched on earlier, dish soap contains surprisingly harsh surfactants, most of which will rapidly dry out blades of grass and cause it to turn yellow, upset the natural balance of nutrients in your lawn, and even linger within the soil for several days.
These surfactants are fine on things like fabric or your dishes or for cleaning dirt and grime off other hard surfaces, but your lawn is far more sensitive to them.
Whether you’re using dish soap to kill off some lawn pests like weevils or grubs or to get rid of weeds or fungal growth in your yard, keep it away from your grass, flowers, crops, and anything else you don’t want the abrasive chemicals to dry out and shrivel up within a couple of days.
However, dish soap also certainly isn’t entirely useless as a method of weed control or as a pest killer.
If you’ve got weeds cropping up in your driveway, for example, a few sprays of soapy water is a clever and inexpensive spot treatment.
Other homeowners have suggested mixing soapy water with vinegar and salt to boost its efficacy as an herbicide and pesticide; just keep it away from your green, pristine lawn.
Does Dish Soap Make Grass Green?
Unfortunately, once again, due to those harsh surfactants, dish soap will not make your grass greener or healthier.
It will dry out your grass significantly, potentially irreparably, resulting in you needing to reseed your lawn days or weeks later once all the soap has finally washed away and is no longer lurking in your soil.
The same goes for any other concoctions involving dish soap, such as mixing it with salt, vinegar, or other commercial products.
They’re fairly effective at killing off certain weeds and insects.
Still, since dish soap isn’t exactly a selective herbicide, it won’t discriminate between your precious bermuda grass, for example, and the ants and dandelions in your yard.
If you’ve ever heard anyone touting dish soap as a means of nourishing your grass or otherwise making it greener or healthier, don’t take their advice.
It will do far more damage than it’s worth, regardless of the brand or type of soap you use, as they all contain the same kinds of surfactants, which are extremely drying and harmful to your entire lawn.
Can You Use Dish Soap To Kill Grass?
Alternatively, you might have the idea of using a whole lot of dishwashing soap to get rid of the grass in your yard completely, so you’re able to start over with a new type of grass.
Based on what we’ve covered so far about dish soap and lawns, it probably sounds reasonable to use it rather than shelling out hundreds of dollars or more to completely tear the grass up with a sod cutter, buy a ton of glyphosate to kill it off, or covering it for weeks with ugly, thick plastic.
Learn about the pricing of lawn care services to help you decided whether to pay someone to care for your lawn or do it yourself.
Unfortunately, while dish soap isn’t good for your grass, it also shouldn’t be used to kill grass permanently, either, as it just isn’t effective enough to completely eradicate it down to the root.
Even if you mix it with vinegar or salt, you still won’t get the results you want when getting rid of your grass completely.
If you use dish soap to kill grass, you will undoubtedly see some results within a day or two.
Patches of grass will dry out and potentially even die off, but one thing to remember about dish soap is it washes away in the rain.
As soon as a storm hits, the dish soap will be washed off your lawn entirely, and you’ll have wasted a lot of product for very disappointing results.
Additionally, products like Dawn dish soap aren’t great for your soil.
While most of it will wash away before it has a chance to get deep into the roots of your grass, there’s a chance some of it will get left behind in your soil.
This will affect the new grass you eventually plant in the same spot and potentially upset the ratio of key nutrients like phosphorus, nitrogen, and potassium.
Does Dish Soap Kill Weeds?
Dish soap is a somewhat effective herbicide, despite being non-selective and a very unconventional means of killing weeds or even certain kinds of lawn fungi.
However, because the soap and its surfactants are equally harmful to your lawn, avoid using it around any plants you want to keep healthy and green.
At best, dish soap should only be used to kill weeds cropping up in your driveway, sidewalk, or in other isolated areas far away from any desirable plants.
As a spot treatment, it’s a good thing to have around in a pinch, but for a long-term solution, stick to actual selective herbicides to prevent doing any lasting damage to your lawn.
Products like laundry soap, dishwashing detergent, or other liquid soap products should also be avoided in most cases.
Does Dish Soap Kill Insect Pests?
In addition to being a decently effective herbicide in certain situations, dish soap is also quite powerful as a means of lawn and garden pest control.
From aphids to slugs to ants and spider mites, the Dawn in your cabinet will easily suffocate both hard-bodied and soft-bodied insects and arachnids within minutes.
The way dish soap works on insects is similar to how it affects weeds and other plants.
Its surfactants strip the insects’ exoskeletons of protective oils, which usually keep them safe and insulated from outside threats.
As the excess soap seeps into their exoskeleton, it eventually penetrates the bugs’ insides, effectively drying them out and suffocating them.
Additionally, when it comes to winged insects, the dish soap solution weighs the pests’ wings down to the point where they cannot fly or escape, resulting in them flailing about in the goopy solution until they succumb to the same fate as non-winged pests.
Again, though, it’s best to avoid using this insecticidal soap solution directly on affected plants unless they are in an isolated location like the cracks of your driveway, sidewalk, or elsewhere away from any plants you want to keep healthy.
Sure, the soap will get rid of your insect problem, but it will also make any grasses, flowers, or other ornamental plants turn yellow, shrivel up, and potentially die off permanently.
This also applies to any other homemade dish soap mixture you might have heard of, like the vinegar mentioned above and salt combo you might have seen mentioned online or heard about from a friend.
Vinegar and salt will make the dish soap a lot more effective insecticide since both ingredients are extremely drying, irritating, and toxic to most insects.
Unfortunately, though, vinegar and salt are also very drying and harmful to your lawn and other plants.
How Should You Apply Dish Soap To Your Lawn?
If you still are thinking about applying dish soap to your lawn, it’s best to only use it in isolated areas away from your crops, pets, kids, flowers, and anything you don’t want to be harmed in the process.
Again, dish soap is non-selective, so it’s not going to discriminate between certain plants and weeds in the same way many commercial pesticides can do.
Alternatively, if you want to test it out on some weeds in your lawn, consider applying a very small “test area” with a spray bottle to the top area of growth of the plant.
Be sure to label the area or make a note of where you used it, so you don’t forget where you applied it later.
This way, the soap likely won’t build up as much in your soil, nor will you have used it in a large enough amount to do any major damage to any grasses or surrounding plants.
This is still a somewhat risky method, but it’s a lot better than simply pouring or spraying the soap recklessly all over your lawn.
If you’re mixing the soap with vinegar and/or salt, be especially mindful of where you applied it, as these products will only make the soap even more drying and damaging to your grass and other plants if it comes in contact with it.
Otherwise, keep the dish soap applications to isolated weeds, using it as a rare spot treatment rather than how you would use other commercial weed killers.
Most popular herbicides on the market are designed to be very selective, so even if you spray them all over your lawn, they’ll only target the actual unwanted weeds.
On the other hand, dish soap is non-selective, so use it with extreme caution on your lawn!
What Should You Use Dish Soap To Kill Weeds?
Like we mentioned earlier, dish soap is fine to kill weeds cropping up in your sidewalk or driveway or other areas which are isolated and far away from anything you plan on keeping around.
The same applies to any dish soap concoctions mixed with other common household products.
When it comes to weeds distributed throughout your lawn, though, you should stick to commercial selective herbicides.
There are pre-emergent and post-emergent herbicides on the market.
Pre-emergent herbicides are designed to kill weeds immediately after they’ve begun to germinate but before they surface on your lawn.
At the same time, post-emergent products are meant to be applied directly to visible weed growth.
There are many different brands and types of herbicides on the market formulated with glyphosate, which is highly effective at eradicating hundreds of different types of common weeds.
Common ones include:
- Ortho Weed-B-Gon
Check out our article on how long Weed-B-Gon takes to dry.
All of these are great choices and, if they are selective herbicides, they are safe to apply directly to your lawn and other plants, as they will only target the weeds specifically.
Non-selective herbicides, on the other hand, are better for eradicating large areas of weeds indiscriminately, for example, if you’re planning on getting rid of the grass in your lawn entirely and starting over with another type of grass anyway or in areas overcome with weed growth to the point where saving anything desirable is a futile effort.
Either way, avoid dish soap in general as a weed killer, as it just isn’t worth the damage it’ll potentially do to the rest of your lawn.