Thank you so much for breaking this down! That also means any soap with a surfactant – which is probably any soap that works at all – would work in this, making it easy to use castille soap, eh?
Awesome! Katie

Shampoo:
I can only assume to be used as a surfactant to allow the spray to stick to the plants as well as to the bugs in order to increase exposure. I think the only reason for baby shampoo is it contains less chemicals, dyes, etc.

Tobacco:
it is common knowledge among gardeners that tobacco deters bugs; making the tea is obviously to get the needed compounds in liquid form to enable spraying, but another option is to actually plant tobacco in your garden. It sounds like many, including myself, here don’t use tobacco for its traditional purpose, but growing these plants in and among your normal harvest may reduce how often, or the amount of spraying needed throughout the season therefore saving you time/effort(?)

Mouthwash:

This patent -(http://www.freepatentsonline.com/5175175.html)

claims that ketones and alcohols, among other organic compounds, may repel insects. However, it also states that some alcohols attract insects. It is difficult in reading that patent to decipher exactly which alcohols do what and why.
I looked on a bottle of Walmart mouthwash here at home to see exactly what alcohols it contained. While it gave no specific alcohols, I found something much more interesting(at least to me, lol). Included in the active ingredients were three organic compounds bursting with garden applications:

Menthol – a phenol known for its pesticide properties, among which include fighting mites that infest honey bees. So that’s a win-win.

Eucalyptol – a cyclic ether and a type of terpene(a hydrocarbon produced by plants), is a well known insecticide and insect repellent. Interestingly enough, it is also quite an attractant/bait for orchid bees as they use it to synthesize pheromones. So…again, you use this and not only are you fighting harmful insects, but you could be attracting at least one species of bee to help in your garden.

Thymol – is a monoterpene phenol that, along with controlling mites, has also been shown to fight nematodes (worms), mold, and fungal spores. I definitely do not know for sure, but logically it could help prevent blight(?)

Anyway, this seems to be a pretty decent little home concoction. I think using the cheap-o mouthwash could diminish the efficacy b/c of either different ingredients or lower concentrations, I’m not sure though.

Another useful tool some may or may not have heard of is diatomaceous earth (food grade), or DE. It is basically fossilized single-celled algae called diatoms. DE is 89% silica and very sharp on a microscopic level. While it is harmless to humans and animals, it is deadly to insects. This completely organic powder will get on insects and as they move, it scratches away the waxy coating on their exoskeleton. After anywhere from 20 minutes to a few hours the bug will dehydrate and die. It is a really neat little thing…quite cheap and has tons of uses(garden bugs, bedbugs, fleas on pets, fed to pets and humans to fight worms and promote intestinal health, etc). I have found the best prices here( less than $30 for a 50lb bag): http://www.earthworkshealth.com/
but shop around and do your own research. Just remember it needs to be food grade.

But thanks for the encouragement! Katie

http://www.herbalremedies.com/organic-baby-soap-castile-soap.html

I’ve read elsewhere that the soap in these types of garden formulas is actually what helps keep the solution on the leaves rather than simply bead off like water alone would. That being the case, I’m not sure how different castile soap acts and if it would be as effective in that capacity.

Hope that helps, and thank you so much for all the wonderful tips and ideas in your blog!

-Chelsea

You are probably right about shampoo not being technically “organic” but more just a “home remedy”. I would hope a fancy organic baby shampoo would do the trick, but I admit I’m not exactly sure what it does. Eating soap makes bugs sick? Or is it breaking the surface tension of water and causing the exoskeleton of the insects to absorb it, thus drowning them? Anybody got an idea?

I wonder if there is a truly safe way to kill bugs, you know? How can we kill one thing and not potentially harm another? Just philosophizing…

Thank you for the challenging comment; it’s thoughts like yours that keeps this blog strong!
Katie