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How to Make Your Own Cheap, Homemade, Organic, Human-Safe Pesticide (Safe Summer at Home #3)

Over the last two years, I really got back into helping with the garden again. The thrill of eating fresh vegetables that I’d helped plant was invigorating. The joy of harvesting some leaves, washing the greens, and enjoying a home-grown salad helped me feel so connected to the earth. Knowing where your food comes from helps you make healthier choices, and growing it yourself ensures you know exactly what went into growing it—what fertilized the soil, how much water and sunlight touched the plant—and makes the literal fruits of your labor taste that much sweeter.

Since the pandemic has made the outside world a dangerous place, I’ve been taking refuge in our backyard. We fought to buy and keep this house because of the spacious yard, and this was the first place where my mother could pursue her dream garden. I started using the back to workout. I have work-from-home conference calls on the patio furniture. I plan meals to cook on the grill and enjoy on the porch. I bought water guns to frolic in the grass with my siblings. I hang laundry on the clothesline. I tie-dye clothes on the patio. I make resin jewelry outside. My world has shrunken due to the coronavirus, but the triumph of taking in that vitamin D right outside my back door—and the rewarding experience of an organic meal that grew a few yards away under my watchful eyes—gives me respite in the midst of the madness.

One of the most heartbreaking parts of gardening, however, is when you go to water the crops and see trampled stalks, uprooted bulbs, and giant holes and bite marks on your precious leaves. It’s been devastating to see so much hard work eaten down to nothing in mere hours, especially from the insidious slugs and mites. You are under attack from the enemy. Rabbits, birds, chipmunks, and insects have declared war on your edibles. What can you do?

For us, we’ve built many barriers for the bigger pests and hung fake owls, bits of colored plastic, and noisemakers to keep them at bay. Salt helps with snails and slugs, but it isn’t the best for the soil in large quantities. We've spent a couple of weeks snipping off affected leaves, squishing individual bugs on sight, and transplanting tender seedlings into unaffected areas, but it wasn’t enough. When it comes to the soft-bodied nibblers, it’s time to wage chemical warfare.

I did a lot of reading to see what pesticides we could buy that would be safe for the soil, safe for the plants, and safe for us since we planned to ingest the plants, but I didn’t much like the options presented to me. Then, I learned about an essential oil that I’ve already seen the benefits of in skincare: neem oil. I did some more research, got some supplies, and got to creating the perfect ratio for our garden’s needs: a special brew that would neutralize the insect infestation, be residual enough to be a repellent, and also deter some of the larger vermin that got past previous defenses. An added fungicidal effect would be beneficial due to the current heatwave and humidity attacking the tomatoes. I ordered everything that wasn’t on hand in bulk so that we can apply multiple treatments and mix the solution fresh whenever we want it, likely once a week this month to quell the pests and as needed afterward. The night before, after a mild, cloudy day, my mother applied our compost mixture to fertilize the garden. The next evening, when all the supplies arrived, I got to mixing and coated the plants after sunset.

What do you need?

Linked are brands I used or recommend.

Why do these ingredients work?

Many commercially-available sprays have ingredients that have questionable effects on humans when we come into physical contact with the liquid or ingest produce that has been treated with the spray (even if you grew it yourself, you should ALWAYS wash your produce well!). This insecticide is extremely potent due to the effect of the neem oil on the bugs: a component called "azadirachtin" acts as a hormone disrupter, reducing their ability to feed, molt, mate, and lay eggs. When the types of insects that eat your plants, the pests, ingest the oil, it will basically just wreck them. Yet, unless exposed to massive quantities of the substance or ingested, neem oil is relatively safe for humans to use, especially when diluted with water or mixed into a carrier oil. It is non-toxic to birds, bees, mammals, and plants, but be wary of using it near aquatic animals.

Hydrogen peroxide boosts root growth due to the extra oxygen molecule, which better enables the roots to absorb nutrients. It also prevents fungi from afflicting your crops, prevents infection on damaged plants, and treats root rot.

The castile soap may seem strange, but its main purpose in the mixture is an emulsifier, helping the oil and water mix. It also helps that bugs just don't seem to like it much, and spraying soap or oil directly on an insect will inhibit its movement.

Eucalyptus oil has a strong smell that repels insects and has antibacterial and fungicidal properties. Tea tree oil shares these properties and is also antimicrobial. Peppermint oil masks the scent of your delicious plants and acts as an irritant. It's also a great ant repellent, disrupting their sensory abilities so they can't follow scent trails left behind by their colony members. All of these oils, by virtue of being oily, will smother soft-bodied insects and slick down the wings of flying ones.

How do you make the garden spray?

To make your very own homemade, organic, pesticidal, fungicidal, pest-repelling garden spray, here’s what you must do.

Wait for a cooler day. Prepare the solution as the sun is setting. You will spray after dark so the mixture won’t evaporate and the oil burn your plants, so you don’t risk harming beneficial pollinators, and so your plants will have time to absorb the water overnight.

First, fill the jar with warm water, leaving enough space for the other ingredients and to shake the mixture. Next, add two tablespoons of the neem oil, two tablespoons of hydrogen peroxide, and four teaspoons of castile soap. If you’re adding the optional essential oils, drop in one teaspoon of each. Close jar tightly and shake well until mixed (solution will be a cloudy white color).

If you have two smaller sprayers, evenly split the mixture between them. If you have one large sprayer, empty the jar into it. Fill the sprayer(s) with lukewarm water to the line and attach to the garden hose.

Water your plants thoroughly with the solution, spraying the ground and stalks, coating the undersides of leaves, and covering blossoms and vegetables.

Your plants will have a lovely sheen to them, which is how you know the neem oil residue is still protecting your crops, and you’ll see fewer and fewer bugs eating away at your greens. When you harvest your goods, be sure to wash them thoroughly with warm water and veggie wash before consuming.

This spray will only keep for a few days, so it's best to scale the proportions to the amount you need to apply that day. If you have an active infestation, use it weekly until things calm down. Then you can spray it once a month or so.


How did this DIY work out for your garden? Have you seen a difference? Do you have any helpful tips to share? What’s in your planters this year? What hobbies have been getting you through the crisis? Let me know in the comments!

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