Failed experiment -- or nearly so, but I expect it to fail all the way shortly. ;-j
I tried dyeing bambu with food coloring in the microwave. I mordanted half with vinegar and half with baking soda (I got a suggestion from one site to do that for the pH). I used black food colorint (really dark, dark green), but when it came time to rinse it out, it all ran away except for a pink. But that's pretty pale and I figure that'll go away too. So no joy.
I think I'll have to spin the bambu white (boring) and then dye the yarn with something designed for cellulose. I know it'll work with indigo with the proper mordant. But that's an experiment for another day.