You usually need a red spectrum light for veg, and a blue spectrum for flowering. Or its the other way around... I forget. And you have to change the light cycles from 18/6 to 12/12 to induce flowering.
Anyway, Im just wondering - if I veg for however long it takes, then change the light cycle to 12/12 to induce flowering, how much will the yield be reduced by if I was just using a red spectrum light? And would it take longer until it buds for some reason?