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With a large plant selection indoors and outside having pesticides on hand is important

Homemade Pesticides get a bad wrap for being less than stellar. But over the years I’ve realized one thing that all of them are missing and that is science. In this post, we are going to break down the DIY pesticides lurking around the internet and find the best recipes that will work for you. The best way to do this is by adding a flare of microbiology and a side of chemistry. So, put your lab coat on and grab your notebook- because we are about to dive deep.

This post was recently featured in a connected to the land blog.

If you are new to this blog my name is Ashley and I am a soil scientist. I am located in a Canadian Zone 3 and a USDA Zone 4. I write articles, make YouTube videos, Instagram & Facebook posts all designed for Canadians and Cold Climate gardeners using science-based methods. If you are looking for anything specific be sure to let me know in the comments down below.

What is a Pesticide? Are Homemade Pesticides True Pesticides?

The term pesticide is broad; it encompasses everything from insecticides, herbicides, fungicides & everything in between. When we talk about homemade pesticides, we can end up with multipurpose control and the fact it is not engineered to attack a specific problem. This is important to remember because it also means homemade pesticides can be harmful if over-applied to our plants. 

Pesticides can be further broken down into application types. Application types can range from foliar sprays to soil amendments. Depending on what critter you are fighting some may work better than others. So, let’s jump into the DIY world of pesticides starting with the soil and working our way up into the foliage.

Mouldy Soil Prevention

Soil mould is common when starting seedlings. This is concerning because some moulds can cause something called dampening. Dampening is a broad term that refers to a host of bacteria and fungi that ultimately results in seedling death. Luckily, there is a homemade pesticides solution for this problem and it’s called cinnamon.

Seriously, the spice you have in the cupboard is one the strongest antibacterial & antifungal solutions for soil moulds. The application is simple. All you do is sprinkle the soil surface similar to how you like your lattes. This can be done before the mould is present or once you notice mould appearing on the surface. Another quick solution is to lift the germination dome off the top of the seedling tray for a few hours to allow for some airflow. This isn’t a homemade pesticide however it is a preventative!

How To Make A Natural Insecticide That Works?

How to make a natural insecticide that actually works can be difficult because it depends on the pest. However, capsaicin spray works for nearly all the insects you can encounter both indoors and outside.

Remember how I mentioned some DIY Pesticides have a kill-all attitude when it comes to pests? This combo is the holy grail of pest control, especially for indoor plants. The recipe is simple. All you need is a spray bottle, 6 drops of dish soap & 2 tablespoons of any pepper you choose. Some suggestions are: Red Pepper Flakes, Chilli Peppers, Dill, Ginger, Paprika, Black Pepper, Garlic (these you can stick the whole peeled clove into the soil)

The theory behind the madness is simple insects cannot survive in areas covered with capsaicin. Capsaicin is found in all the herbs listed above and is what causes “the burn” when you rub your eyes, skin or mouth after touching hot pepper seeds. Needless to say, that irritation is passed onto the insect and they enjoy it about as much as you do. This is the homemade pesticides group that “bugs the bugs”.

Dish Soap As A Pesticide Is Making Things Worse…

The soap also plays a major role in pest control as well. Soap will help to dry out any larvae on the leaves. And it will be able to help the pepper of your choosing stay in place. One thing to keep in mind is that this can leave the plan open to over infections due to the removal of the cuticle.

The best way to apply this is manually. Simply spray down the leaves both top/bottom and the stem. From there take a washcloth and gently remove the excess water. The process of wiping off the leaves will help remove any dust build-up, fungal spores & bacterial colonies that may harm the plant.

It will also allow for better photosynthesis & ultimately a healthier plant. You can use this mixture as a preventative once a month or during an active pest invasion once a week.

Can vinegar be used as a pesticide?

Vinegar can be used as a pesticide on the leaves of plants but never apply it to the soil. Always proceed with caution when using something with a pH that is not neutral. Leaves on plants are considered semipermeable and will absorb leaf-placed substances, such as vinegar.

If you choose to use vinegar as a pesticide you want to apply it only to the tops of the leaves. Most plant leaves have their stomata located on the bottom. We want to avoid placing vinegar on the bottoms where the absorption is the highest.

Homemade Herbicides: Weeds & Vinegar

Vinegar is the only herbicide to make the list and that is because it’s really the only herbicide you need to use. Word of warning: do not use vinegar near plants you want to keep around, it shows no mercy. This is a simple homemade herbicide; full strength sprays or pours it right into the weed in question. Within a few hours, the weed will no longer be an issue. I commonly use this on sidewalks & brick areas because it’s pet & child friendly.

What Is A Good Homemade Insecticide?

When looking for a good homemade insecticide there are specific properties we want to see. Homemade insecticides need to be able to prevent adult insects from feeding, stop larva or pupa from surviving or cut off the food source entirely. Most homemade insecticides on the internet such as using dish soap can actually make the issue worse by thinning out the plant’s cuticle. This leaves the plant open for infection and the potential for a worse infection.

Good Homemade Insecticides:

Cautioned Homemade Insectidies:

Homemade Organic Pesticides

When looking for a homemade organic pesticide you can use any solution that is made up of organic vegetation and non-chemical compounds. Mouthwash and dish soap would not be considered organic homemade pesticides. However, capsaicin spray, organic beer or sugar/baking soda would be considered organic pesticides.

Homemade Pesticide For Ants

A homemade pesticide for ants that is simple and effective would be a 50/50 mix of baking soda (or borax) and sugar. This can be placed near the area infested with plants and within a few days, you will have drastically lowered your ant population. If you are looking for an organic biological method that doesn’t involve reapplying after every rainfall check out my article on Nematodes.

People will often argue that ants are a valuable part of a garden ecosystem. This is absolutely correct because they not only act as a predatory but also help with soil aeration. However, ecosystems are about balance and in the concrete jungle we can end up with an overabundance of even the good stuff. Managing an ant population is a human and eco-friendly way of keeping your garden ecosystem in balance.

Homemade Pesticide For Indoor Plants

Homemade pesticides for indoor plants are essential for emergencies. One of the issues is that homemade pesticides are not always the most effective. When we apply some basic plant science, however, we can gain insights into what will really work!

Good Homemade Insecticides:

Cautioned Homemade Insectidies:

Homemade Pesticide: Slugs, Snail & Beer

This was a must-add DIY because beer is a must-have tool in a gardener’s arsenal. This trick is for slug & snail prevention and it works a little too well. All you do is take a pie plate and place it in the problem area with an inch or so of beer. Turns out slugs and snails enjoy visiting beer gardens; the only issue is they rarely leave the bar…

All joking aside it does work, but you will need to dump the mini murder scene every day and place a fresh trap until the issue is resolved. 

If you are wanting more information on this check out my YouTube video that goes into more details.

Here are some other gardening and plant care tips you may enjoy!

Gardening In Canada