DIY Pesticides… Are They Safe
ORIGINALLY FROM DECEMBER 2020, UPDATED JUNE 2026
I regularly meet people who admit to using homemade concoctions as pesticides and I’m appalled at what they’re mixing up. While many gardeners think it’s safer to use household items rather than store-bought products, it’s not. It’s causing harm – often unintended – to your plant’s health, your garden, and the ecosystem beyond. To understand why, let’s dig more into what a pesticide is and its intended use.
What is a Pesticide?
All pesticides are designed to kill something. Whether it’s DIY, synthetic, or store-bought, the goal is the same. But you might be surprised to know that, when used according to the label on the targeted pest listed, commercially-available pesticides can be more efficient and less harmful to the environment than something made at home. This is because store-bought pesticides are tested against target pests and formulated specifically for plant use (unlike ingredients like vinegar or dish soap used in many DIY concoctions).
DIY pest solutions, including homemade weed killers or herbicides, may not be as safe as you think.
When you create a mixture at home to kill or repel insects with, you’re making a pesticide. DIYing it doesn’t make it safer, it’s still a pesticide intended to kill. And when you make it from a recipe you find on social media, there is a lot of room for error to you and the plant, not necessarily to the pest.
Why DIY Pesticides Aren’t Safer
I was on a call with a friend the other day. She mentioned that she’s been spraying newly developing weeds growing in the cracks of her walkway with the widely popular vinegar, dish detergent, and salt recipe. Wonderful since the best time to manage young weeds is when they are newly sprouted. Unfortunately, this trending internet recipe does more harm than good.
Don't get me wrong, I appreciate the sincere intentions to reduce pesticides. However, these kinds of recipes are a huge concern and very much misunderstood. Let’s dig into the 3 reasons why.
1. Dish detergents are not true soaps
The only true soap on the market is castile soap, under the brand name of Dr. Bronner’s. There may be other brands bottling castile soap, but they’re not always easy to find. Unlike true soap, dish detergents contain degreasers and many harmful additives such as:
Methylisothiazolinone: highly corrosive and found to be toxic when ingested or inhaled, it also causes skin irritation/allergies/damage and acute aquatic toxicity
1,4-Dioxane: listed as a likely human carcinogen and a groundwater contaminant
Ethanolamine: listed as harmful if swallowed, including respiratory effects, general systemic/organ effects, chronic aquatic toxicity, nervous system effects, and skin irritation/allergies/damage
Triclosan: listed as causing developmental/endocrine/reproductive effects, cancer, immune system effects, circulatory system effects, nervous system effects, skin irritation/allergies/damage, digestive system effects, and having acute aquatic toxicity
And that's not all, many have words like “natural” on the label but have added scent and coloring that are chemicals showing health concerns. When you use these types of dish detergents as an additive in your DIY weed killer or aphid spray, you’re contaminating the soil. And yourself.
You’re also risking the health of your plant! Degreasers can strip the protective coating on plant leaves. This can cause brown or black spot in the following days that are usually mistaken for a fungal problem. As a gardener, you want to be able to make the right identification of a potential problem so you can treat the root of it… a DIY mixture gets in the way of that.
2. Salt is bad news for your garden
Salt in the soil absorbs water, which reduces your plants’ ability to take up water and increases root dehydration. You might think this is exactly what those weeds need. Keep in mind that if you ever want to plant in that soil, you may see your plants struggle or even die because of this salt build up.
Let's look back at our history books. Remember how the Romans and other invading armies would burn a village down then salt their fields to prevent crops from growing again? This is why. You want to avoid adding salt to your soil if you want to grow lovely plants. This includes using synthetic fertilizers, which are very high in salts. Feed your plants organic fertilizers for optimum health.
3. Vinegar is much too strong
Household vinegar is diluted to about 5% acetic acid, while horticultural vinegar is around 20% acetic acid. That’s pretty strong! 11% acetic acid can burn skin and cause eye damage, while concentrations of 20% or higher can cause blindness and are corrosive to metals.
Something else to understand is when vinegar is used as a weed killer, it is working as a “top kill herbicide,” killing the top leafy part of the plant tissue. This is why, when using many of the eco-herbicides that are sold on the market, it’s best to apply when the weeds have just sprouted so the root can’t recover and sprout new growth.
So if homemade concoctions aren’t advised, what are your options?
How to Manage Weeds and Other Pests the Eco-Friendly Way
Let’s look at another example I’ve seen of a DIY pesticide: neem mixed with rubbing alcohol and dish detergent. A lady I met was trying to kill spider mites on a $200 houseplant in her bedroom. I mentioned that the rubbing alcohol is flammable and she shouldn’t breathe it in. She said that she wore a gas mask… lord have mercy!
I saw her the following year at the same event and she thanked me for my sound advice of increasing the humidity and circulation in the room. When she did, the spider mites vanished. No homemade pesticide mixture needed. The same line of thinking can be applied to your garden.
The best way to get rid of weeds and pests on your plants is to adjust the environment to make it less desirable for them to grow. This IPM approach involves starting with a foundation of healthy soil, using proper watering techniques, planting appropriately for your climate, and feeding organically. It also shows us that healthy gardens have pests in small quantities to feed garden allies and maintain a balanced ecosystem.
Hand pulling weeds, using weeding tools, and sheet mulching can't be beat for best ways to manage weeds. If you want to use an eco-friendly DIY method then I'll share a little trick… boiling water! Boil up a kettle of water, grab your oven mitt, use caution to not burn yourself and douse those weeds. Just like the DIY recipe, you will most likely need to repeat this as needed, but without the cost or potential harm to your garden environment.
Ways to Grow Together
This is your friendly reminder that DIY pesticides are not safer than store-bought ones. In fact, they can be more harmful to the plants and beneficial insects in your garden since they’re untested against target pests and not formulated for plant use. The good news is that you can manage weeds and pests the sustainable way – no pesticides needed.
Want to dive more into how to keep pests at bay without using toxic chemicals? Here are 2 blogs that can help: