Green bulbs work fine. But as stated, best to keep it as limited as possible - just in case lol. Green is kind of a part of the light spectrum plants don't seem to really pick up, they utilize more of the red and/or blue parts of the spectrum - Although I have no scientific facts to back that up, so feel free to ignore it! Hahaha.
My hydro shop sells green bulbs for this purpose so I suppose they really do work, although I've never tried them myself.
Cheers.