10 to 12 large cloves of garlic
4 to 6 hot chile peppers, dried or fresh
Generous 2 cups water
1 tablespoon liquid castile soap (like Dr. Bronner’s), Basic H ™ (Shaklee), or any biodegradable liquid dish washing soap
I have been making this spray for more than 20 years–I don’t remember where the idea came from–perhaps an old issue of Organic Gardening or Mother Earth News. I do know that the recipe works. It is not an exact science; use a handful of dried cayenne peppers or other hot chiles and about a bulb of garlic to make the base concentrate. Mix the concentrate with water and spray it on plants with an infestation of aphids, mealybugs or white flies.
Every year, I move all of my plants out of the greenhouse for the summer. Before moving them back into the greenhouse after spending the summer outdoors, I routinely spray them with this spray before bringing them back inside; it makes all of the critters take off and leave. My herbalist friend Tina Wilcox adds 10 drops cinnamon, vetiver, or eucalyptus essential oil to this concentrate when she makes it.
The recipe is loose; it makes about 3 cups of concentrate.
Put the garlic, chiles, and water into the blender and blend until the garlic and chiles are pureed. It will make a lovely orange-pink concoction that is foamy. Let stand for at least 2 hours or overnight.
Once it settles it will separate and you will have a coral-colored liquid with sediment in the bottom. Pour the mixture through a strainer lined with fine cheesecloth, through a coffee filter, or even a jelly bag; this takes a little while to strain. You can also use a wet paper towels, however this takes even longer to strain. The idea is to get rid of all of the particles because they will stop up the valve of your sprayer.
Once strained, pour the concentrate into a jar with a plastic lid (not metal), add the soap, stir, and label. The concentrate is ready to use, or it can be stored in a cool dark place for a few months to be used as needed.
Our spray bottles holds about a liter (or a quart), so we add about 2 tablespoons of the concentrate to the bottle and fill it with water. We spray the plants late in the day, so that hot sun doesn’t shine on them once they are sprayed, making sure you cover both sides of the leaves. If the hot sun shines on the just-sprayed leaves it can burn them. Also if you use too much concentrate it will also burn the leaves. If you have a serious infestation, you will need to apply the spray a few times, waiting a few days in between.