You know, I have the same issue you have: my grays grow in fast, like weeds Like you, I add amla to my henna mix (but no indigo).

I'm also thinking about hennaing my roots more frequently but it's so hard to only get henna on the roots. I know it will relax any already hennaed hair, even w/ amla in the mix. I know this because that's what happened when I hennaed my whole head. The fact that it acts as a relaxer (due to build up) is what's keeping me from doing weekly treatments.

That said, sounds like your hair may be more resistant to henna's relaxing effects. Still, it's a risk and you could lose curl if you re-henna parts of your hair. ... Maybe you could increase the amount of amla in your mix? That would further mute the color to a cooler, possibly darker shade (I'm considering this tactic ). To compensate, you could try using less indigo, perhaps. I would call the folks over at the henna forum and ask them about all this. They also have a phone help line. It's where I turn for henna info.

Ringlet Fandango! ... Where curly ideas roam free

* 2 blogs this week: Pictures of My (Sorta) Big Chop! AND Turn a Nightmare Product into a Dream* My Albums