Have been searching for decent biodegradable shampoo & conditioner. At a minimum, was hoping to find something good enough to use when camping, but really wanted something to use at home as well. Nothing I tried worked well enough that I wanted to use it again, even for camping. Did keep searching though. That's how I came across the idea of using baking soda in place of shampoo & apple cider vinegar (ACV) as a rinse. To my considerable surprise, it works for me. Have used this approach for the last couple weeks & will probably continue. Will likely use my regular, sulfate-free shampoo & conditioner once a week or so. The baking soda & ACV are at least good enough to use on their own for a week or two. That gives me a cheap & easy, biodegradable substitute for shampoo & conditioner. Below is my approach & experience.
It seems most people who use baking soda liked it at first but found it dried out their hair when used long term. I figured it was worth a shot. To my surprise, it works pretty well. Most people seemed to be using a lot more baking soda than what works for my hair. I put a teaspoon of baking soda in a 4 ounce bottle & filled it with water. The baking soda doesn't seem to dissolve so I have to shake it well each time I use it. I applied it by just pouring a very small amount onto my scalp in about 4 spots, top, right, left & back of head. Scrubbed it into my scalp as best I could then rinsed it out well. It got my hair squeaky clean. It was too squeaky, actually. So that's why I used I needed a conditioner or rinse of some sort. I estimate I'm only using less than 1/4 tsp of baking soda each time.
Had used apple cider vinegar on my long-haired dogs before so decided it might be worth a try for my hair. Just happened to have a little 2 oz spray bottle left over from a travel kit. Just poured the ACV into the bottle & sprayed it onto my hair. It didn't take a lot, maybe 1/2 oz or less. Then I rinsed that out & did my hair styling routine as usual. It seems to work well. The only downside is that the vinegar smell lasts for about 30 minutes so. Then I found out that if my hair gets wet again later that day a faint vinegar odor reappears for a few minutes. However, neither of us can detect an odor after that. It's rather surprising.