Basically I rarely use shampoo, and then only a dab at the crown of my head. I also use a boar's hair bristled brush to distribute the natural hair oil to the ends of my hair. This may sound gross, but research it. You will be surprised at what you find. That is exactly what happened to me (See thread on my experience with 'No Poo' below). Now my naturally curly, frizzy hair is a delight. No more gels, mouse, cream rinse, hair spray, or silicone smoothers. Who knew going bare natural would wipe out a whole shelf of hair care products?! These days I use castile soap when I need a bit, which is about once a month, if I do my water only washing with each shower I take. By the way, when I researched how things were done in the late 1800s to early 1900s, I found a quote that stated "Pure soft water is all my hair and scalp have ever needed".
Just a note in case you don't want to read about my 'No Poo' experience: Soft water really makes a difference on how long I go without shampoo.
There are many who use baking soda and vinegar. I won't say much about that since my experience with it is minimal, but when done right, it does give satisfactory results. I am working on finding other means, sustainable at home means, for washing hair. So I will keep you posted once I make another worthwhile discovery.
Update May 2015
I am currently doing what is called Low Poo right now because our water is so hard and I am trying to grow my hair out. There has been an increase of helpful information on the web about various methods. There is a facebook group that has compiled many resources. it is a great place to ask questions and see what others have experienced. Look for "No Poo & Low Poo Hair Care Group Forum," to start your journey to better hair.
Update 4-16-13 Scroll down for original forum thread.
Yes, I used tomatoes to wash my hair. I must say the results have been nice. I found others on-line who use tomatoes as a conditioning rinse, but I used them as a cleansing shampoo. My hair felt like I had used an all-in-one Shampoo/conditioner. If you are use to using a castile shampoo, this will be similar. I add essential oils to give a nice scent. Lavender and Lemon Grass combined very well. , with different things, you may just find the perfect shampoo. I even added some onion a few times. Onion has sulfur which is good for your hair, but my husband and I both wanted Italian food after I came out smelling like tomatoes and onions. The smell does not last a long time, though.
You can use any form of tomato from fresh to paste. There are, however, some warnings that I should share with you before you begin.
Fresh Tomatoes seem to be the best option, but make sure you peel and de-seed them before blending them smooth. Otherwise, you will be brushing seed and skin peeling flakes out of your hair for a few days.
Tomato Sauce is a good option for when you are in a hurry. Tomato Paste works as well and is usually more cost effective. You will need to thin the paste out with some water to make it more the of sauce. The warning on these options is that it will stain (cooked tomatoes). That may not be an all bad thing if you like pink/redish hue highlights. My gray/brown hair looks better with the tomato highlights. Just be aware that the staining does rub off on clothes and pillows. The fresh tomatoes do not do this.
Once you prepare your tomato, put it in a squeeze bottle. Apply it to your hair wet or dry. Process through just like regular shampoo (no foaming bubbles), then rinse out and style as usual.
I have also use Cucumbers and Lemon. It was cleansing, but a little less moisturizing. So I stick to tomatoes, but the combination worked well for my husband. The same rules apply to this as to fresh tomatoes; Peel and seed them before blending smooth. You should use a large cucumber and the juice of a very small lemon. It smells great if you use it right away. If it marinates, you will smell like pickles, so you have been warned.
Once you prepare your cucumber and or lemon, put it in a squeeze bottle. Apply it to your hair wet or dry. Process through just like regular shampoo (no foaming bubbles), then rinse out and style as usual.