For me it indicates a nutrient imbalance. I've had this occur before but I didn't notice a diff. in yield. I've also grown some Afghani that produced purple buds in about 20% of the plants. Of course this had nothing to do with the veins, but thought I'd throw it in here.
grey1223 Reviewed by grey1223 on . PIC of The Dreaded Purple Vein Sativa! hahahaha here it is guys ... i aint complaining i love the colour through it, it loooks awesome and reminds me why i love plants so much ! peace guys Rating: 5