Got bugs? Here’s how to make your own homemade insecticidal soap so you can save money and get rid of pests on your plants whenever you need to.
Best of all, by making your own insecticidal soap, you know what ingredients are going into the product. This ensures that there are no toxic chemicals, artificial ingredients or additives that can harm your plants.
In this guide, I’ll explain everything you need to know about insecticidal soap, including what it is, how it kills insects and pests and how to create your own DIY insecticidal soap at home with just a few ingredients.
What is Insecticidal Soap?
Insecticidal soap is a liquid solution that’s often applied in spray form to plants to eliminate pests, bugs and insects like spider mites, mealybugs, whiteflies and aphids.
While it can be used to clean a plant’s leaves, this is not its main purpose, and it is rarely used to do so. Instead, gardeners use insecticidal soap when other simpler methods like hosting off pests or picking them manually don’t seem to be effective.
You can purchase ready-to-use insecticidal soap spray containers from your local garden center or in home improvement stores. Although many growers will also create their own homemade DIY insecticidal soap sprays at home (I’ll give you a few recipes below) to save money.
The soap solution used is designed not to be harmful to plants. However, if you’re making your own insecticidal soap solution, you want to make sure that it is not too potent as this can burn the leaves of the plant.
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How Does Insecticidal Soap Work on Plant Pests?
The active ingredient that makes insecticidal soap effective against pests and insects is potassium salts of fatty acids. This suffocates soft bodies insects like thrips, scale, aphids, spider mites, mealybugs and other pests and insects.
When these fatty acids come into contact with their torsos, the compounds penetrate and break down the protective outer cell membrane and exoskeletons (waxy coatings). This causes them to lose the water their bodies hold which keep them hydrated. As a result, they die from dehydration.
More importantly, it means that spraying insecticidal soap on leaves regularly when you can’t see the pests is not effective because the solution needs to come into contact with the bugs and insects. Only upon contact will it be able to get rid of them.
Another important thing to consider is that insecticidal soap is only effective when wet. So, you want to directly apply it to the pests themselves. Once the solution dries, it loses its potency against insects and pests.
If you look around the internet, you’ll see many different soaps used as the main ingredient. I like to use castille soap, like Dr. Bonner’s Castille Soap, because it contains the potassium salts of fatty acids. Although, many others will recommend using dish soap like Dawn.
The biggest different between insecticidal soap and commercial pesticides found in stores is it does not contain any toxic chemicals or residue. This makes it safe to use in houseplants as well as the garden even in the presence of young children and pets.
DIY vs. Commercial (Ready to Use) Insecticidal Soaps
Since we’re on the topic of commercial products, it is worth spending a little time to discuss the difference between the ready-to-use commercial insecticidal soaps you find on store shelves and homemade DIY insecticidal soaps.
Like all things, both have their pros and cons.
Ready-to-Use Commercial Insecticidal Soap
Commercial insecticidal soap comes in spray bottles, much like the many home cleaning products do. This makes it easy to use. All you need to do is open the packaging, point and spray.
They can cost anywhere from $5 or higher for a 32 ounce spray bottle. It all depends on the brand and what ingredients they use.
In any case, the biggest advantage of these products is they are very convenient. There is no mixing involved, no figuring out the right ingredients and percentages. Everything is already mixed well and ready to use.
This concentration is very important since they’ve tested it to be effective against pests and insects. And, they’ve made sure that it won’t damage the plant.
As mentioned above, too much active ingredients or potency can damage the plant as well. So, its not all about pest killing power. That needs to be balanced out, so you don’t harm the leaves in the process.
This also means you want to check the label of each product before buying. Some will say “Organic”. Others will say “Safer for Plants and Vegetables” and so on.
When it comes to ingredients you want to look for the terms “Potassium salts of fatty acids” or “Potassium laurate”. These are the active ingredients that will eliminate the pests.
A final thing to note is that some products come in concentrated solutions. This means you need to mix them with water before using. That’s because they’re more pure concentrations. Directly using these products will damage your plants because they’re just too strong.
As such, you’ll need your own sprayer as well. That’s where you put the mixture after you’ve added water to it. Then, spray on the pests.
Concentrated solutions are more expensive about $15 or more for a 32 ounce bottle since you get more of the product since there’s not water added yet.
If you’re on a budget or looking to save money, this is a better option. While a bit more expensive in nominal cost, it actually makes 5 or so more times spray (after water is added) that the pre-mixed ready-to-used bottles.
Homemade DIY Insecticidal Soap
The best way to save money with insecticidal soap is to make your own. That’s why many growers create their own homemade DIY insecticidal soap formulas.
The good news is, it is very easy to make. You only need a few ingredients. And, the steps are fairly simple.
The bad news is, you need to do a bit of experimenting and learn how to mix it properly. That’s because water and oil don’t mix. You probably already know that by observing how water and the excess grease in pans don’t seem to mix well together.
Additionally, it is important not to overdo it.
Too much soap concentration compared to water will give you a more potent bug killer. But, it can also damage the leaves of the plant which solves one problem but creates a new problem.
So to help you avoid the pitfalls, I’ll break down the ingredients, mixing instructions and how to apply your own homemade DIY insecticidal soap in the following sections below.
How to Make Your Own Insecticidal Soap
In this section, I’ll give you a couple of homemade DIY insecticidal soap recipes you can use. Both work.
But, I prefer the first one since it is safer to use with no risk to your plants. However, it also costs a little more and you’ll need to go out and get castille soap since it is not a regular household item.
Option 2 on the other hand uses dish soap, which is cheaper and something you already have in the kitchen. But, you do need to be more careful with it because too much can be harmful to your plants.
Option 1: Homemade DIY Insecticidal Soap Using Castille Soap
This is my go-to formulation for making DIY insecticidal soap at home.
Here’s what you need.
- Soap – I like to use Castille Soap. My favorite is Dr. Bronner’s Pure Castille Soap. It is a liquid soap that you can mix. Other brands that work really well as Quinn’s and Cove. At least these are what I’ve tried. I like to use the unscented version but there are scented ones as well. These contain the active ingredients mentioned above with organic oils that will get rid of pets. Castille soap is also more refined (and different) from dish soap or detergent).
- Tap water – avoid hard water. if your tap has a lot of added chemicals like calcium, fluoride and other chemicals (which many municipalities add) you can use distilled water or rain water. Many plants are sensitive to high chemical content in water. Also, hard water reduces the effectivity of the soap. Another option is to let the water sit in room temperature for at least overnight to 24 hours. This will let the chemicals evaporate before you create your insecticidal mix.
- Sprayer – you can use a bottle sprayer or a pump sprayer. This one is up to you. As long as it is able to spray the solution so you can hit the pests either is fine. Remember, your solution needs to come into contact with the pests so a poor quality sprayer that has no precision isn’t helpful.
- (Optional) Vegetable Oil – this helps the solution stick to the surface longer. It also prevents the solution from drying too quickly. But, you need to mix properly since oil does not mix well with water. Also, since oil goes rancid, it is not a good idea to make a huge batch unless you have an infestation problem. Instead, make a new batch when you need it.
- (Optional) Natural Scents – you can add natural scents, ideally using things that will repel bugs, pests and insects. Depending on what you want to get rid of, you can use peppermint, eucalyptus, lavender, garlic, vinegar, or pepper.
To Create a 1% Soap Solution
You can create a 1% or 2% soap solution. Obviously, the latter is more potent. But, it also increases the risk of plant damage especially for more delicate foliage plants.
So, always makes sure to test on a small part of the plant before applying it everywhere. That way you know when you spray on the bugs it won’t burn the leaves in the process.
Starting with a 1% soap solution is a good, safe option. Again, you can increase the concentration or dilute it with more water to reduce the concentration.
To make a 1% soap solution for pest control, mix
- 5 tablespoons of castile (pure) liquid soap
- 1 gallon of water (avoid hard water)
Then shake well to mix them together.
As mentioned, you can add natural scents if you want using those mentioned above. These repel bugs as well as add some aroma to your solution.
You can also add 1 tablespoon of vegetable oil to the mixture above if you find that the soap solution is not sticking to the leaves long enough to affect the pests.
But, if you do add vegetable oil, keep it in mind it gets rancid after a while, so make smaller batches and fresh ones when you need it.
Otherwise, if you find that the solution is sticking well enough and doing the job, just go without the oil. This way you can keep a larger container that’s ready to use when you need it.
If you need to scale up the volume, add 2 teaspoons of castile soap for every 1 quart of water.
Option 2: Homemade DIY Insecticidal Soap Using Dawn Dish Soap
If you need to make an insecticidal soap now but don’t have castile soap or don’t want to spend extra money on castile soap, here’s a budget option.
Do note that I recommend option 1 more than this option because pure castile soap does not contain any artificial chemicals, synthetic ingredients, degreasers or other extras. That’s not something you can always be sure of with commercial dish soap products.
Often, dish soap or dish detergents contain scents to make them smell good, dye coloring and other additives can be very harsh on plants. So, you want to be more cautious when using dish soap compared to castile soap.
That said, it does work to get rid of pests from your plants.
Here’s what you need.
- Mild liquid dish soap (Dawn liquid dish soap)
- Tap or distilled water
- Vegetable oil
- Spray bottle or pump sprayer
The overall process is just the same as above. But, this time you’ll mix:
- 5 tablespoons of liquid dish soap
- 1 gallon of water (avoid hard water)
- 5 tablespoons of vegetable oil
Load all the ingredients into the sprayer or a mixing container then shape well. Since the oil will separate from the water, make sure to shake well before each use.
How to Apply Insecticidal Soap to Your Plants
Now that you have the insecticidal soap ready, it is time to apply. But, before you do so, keep in mind a few things.
Hot or dry conditions make plants more sensitive to soap. So avoid applying when the it is very hot. The higher temperature goes, the more stress plants experience. This makes them more susceptible to damage.
I like to apply in the morning since it is cooler during that time of the day. You can also do so at night or late afternoon. But, be careful not to wet the plant too much because it can cause more problems later on.
Also, move the plant away from everything else. Spraying is not an exact science. And, from experience, you’ll end up over spraying a bit here or there. So, I like to move the plant away from everything else before spraying.
Again, don’t spray indiscriminately. You need to hit the pests with the solution for it to be effective. Thus, covering the leaves with soap solution is as waste of time and effort (and soap).
Finally, it takes a while before you eradicate or see improvements. Once a well is a good frequency to start with. But for more serious problems you can apply once every 4 or 5 days.
Avoid doing it too often (more than once every 4 or 5 days) in the same places since this will eventually damage the leaves.
If you see any damage or injury to the leaves, dilute the solution with more water.
I suggest testing it on each plant before using since different plants have different sensitivity levels. It takes 24 to 48 hours to see any effects. So start with small portions and check for brown or yellow discolorations on where you sprayed.