Just use a nitrogen supplement in addition to bloom nutes. I use just enough to make the yellowing of the leaves go away. too much N will hinder flowering, so will an N deficiency.
be careful of dead/dying leaves. Its a great place for mold to take hold.
I do a tug test on my leaves when they look like they are getting close. If you can tug gently and the leaf comes off, it was time for it to go.
By using nitrogen throughout the flowering process, you should only see yellow leaves at the end of flowering when you cut back food and plan to flush.

hope this helps.
GanjaRobPDX Reviewed by GanjaRobPDX on . First Grow - Kalishnikova (WhiteWidow/AK47) Start to Harvest - Any guess on Yield? Hey guys, Today I am chopping my Kalishnikova plants. I am not 100% sure they are ready, but they are acting a little funny so I am playing it safe. As you can see from the pic literally every large and medium sized fan leave has yellowed and fallen off. I would say 25% of it occured last night. Trichs are 75% cloudy 25% clear and I cant find a amber one. 10 weeks and 2 days of Flowering. Fox Farm Soil Canna nutes (Terra Flores, Vega and Boost) 1000w HPS Hortilux Grown from seed bought Rating: 5