I have a sativa (80%) that is 6.5 weeks into flower and have yellowing leaves. The seed company say they are mature 9 weeks from 12/12 switch. I believe this is fairly normal but would appreciate your thoughts. This strain usually goes about 10-11 weeks for me but this grow is the best i've done. What are your experiences and should I be concerned with 3-4weeks to go and if so should I up the nitrogen or leave?