I never had greasy hair when I switched to a no-poo/low-poo lifestyle. Yes, your hair will be a little flat at first but it shouldn't be greasy. You wash your hair with conditioner instead of shampoo. It's called CO-wash, or conditioner-only wash.
I really recommend this web site for everything you need to know about a no-poo/low-poo, or "Curly Girl" lifestyle.Or you can ask me anything. I've been doing this for 4 years now.
The website is www.naturallycurly.com. Here's a link to an article about CO-wash:
Re: Nopoo-ers: You don't have to have greasy hair!
This is true!
But in order for this to be true you also have to make sure your conditioner does not have any silicones in it and that none of the products you're using have silicones because otherwise you will have build up. (That's why, with Wen, you should periodically clarify your hair.)
This chick has a list:
http://sites.google.com/site/ladylonghair/%27cone-freeconditioners
ETA - you really have to scrub your scalp, too, for a few minutes and then run your fingers through your hair when rinsing to make sure you're thoroughly cleaning your hair.
I do a combo actually...DEVA lowpoo or no poo, plus the DEVA conditioner. On some days I just do the conditioner.
The key is NO sulfates and NO silicones..the silicones is what people complain about re: greasy hair. And the biggest issue is Loreal and these other brands claim no cones or sulfates, but if you look at the ingridients it is there..just maybe lower on the list.
Know your products/research.
I think if my hair was either curly or darker in color, it would never appear greasy doing conditioner-only. Straight, blonde hair looks dirty & stringy really easily, though, so every couple of weeks I might use shampoo for a re-set.
Ditto the scrubbing your scalp really well with the conditioner, too. It's kind of liberating, since ironically I always tried to condition my hair very lightly / only on the ends specifically to prevent my hair from getting too flat. Oddly, I seem to have less of problem with this now that I skip the shampoo.
Truer words have never been spoken! I'm currently waiting on a bottle of Hair One Peachy sent me, I'm so very curious how my fine, thin blonde hair will react.. stupid Canada making EVERYTHING hard to come by.