For the past year I have been trying one of my year-long experiments. This year's was not as successful as the standing desk, which I'm still using.
No, this year's experiment was washing my hair with baking soda and apple cider vinegar instead of shampoo.
I have made my own deodorant and toothpaste from baking soda (and other ingredients)- and they worked OK, but there were always issues*.
And, when I say "not as successful", I don't mean there was any real problem. I honestly can't tell a difference in my hair after using no shampoo, but only baking soda and apple cider vinegar for a year.
So, while I'm glad there was no problem, considering the extra work, I think I'll just switch back to shampoo and conditioner. "No difference" translates into "no reason" in this case. Shampoo and conditioner are just faster and easier. Yeah, they may be slightly more expensive, but since using the "natural alternative" takes longer to wash out, I wonder if the extra water usage eliminated any economic benefit.
Plus, if you can't easily make baking soda at home in the event of TSHTF, it's not really a survival technique anyway. Yucca leaves and roots might fit that bill better (or other things, depending on your location). I would say it's best left to those times you ran out of shampoo, don't want to use your soap/body wash for some reason, and have the ingredients at home.
Just another bit of data to keep in the back of your mind, but don't spend much time worrying about it one way or the other.
-*The deodorant was crumbly. It was too hard when cold and too soupy when hot. That's the coconut oil. It did work pretty well, though.
The toothpaste also worked. It was also affected too much by temperature- often either flowing out of the tube as a liquid, or too hard to squeeze out.