butterflycayton, that was my question when i started this process. i wanted to blend my previously bleached blonde highlights with my natural hair colour growing in - natural color is a mousy, light brown or possibly even a very dark ash blonde. i have not been able to find a mix of henna and buxus, or henna and indigo, that will produce a sufficiently ashy light brown. the buxus is closer, but it fades, and there's no way to stop that. for most, indigo will stick (though possibly not on the first application), however, it seems difficult to get a light brown with henna/indigo - if you use enough indigo to counter the red of the henna, you've got at least a medium brunette going on. the only hopeful bit of info. i found was that one person used the henna with boiling water, then mixed with twice the amount of buxus, and got a neutral, lighter brown. however, she found that the entire colour faded after several washes. i was gonna go back to chem dyes because of this - but have been checking into other, natural sources of brown - think i will give catechu, walnut, and other natural dyes a bit of a chance before going back to chem. it can't hurt to try them!