Lookin' good bro! I don't have allot of luck with edibles either, but I've lost part of my stomach and small intestines so I figure that probably has something to do with it. Some Rx medicines have to be "dose-adjusted" for my issues, so I guess the MJ edibles are the same way.
Yep...definitely a N def bro! If it were me, I'd hit 'em pretty hard with the Grow Big and as severe as the def is...I'd foliar feed as well. I doubt you'll ever get it completely caught up, but maybe you can preserve your fans and make it thru flowering. If you DO foliar feed, I'd separate the plant out, spray her down really good, making sure to get the undersides of the leaves with as fine a mist as possible, and then I'd take it out from under the direct light and move it off to the side. I'd keep her there until she dried off completely. Id also put a fan blowing directly on her until she was completely dry. I also think you're best off foliar feeding right when your lights come on. Just be sure not to keep her under direct light until she's completely dry, or it can burn her leaves.
Normally, I never foliar feed or spray at all in flower, unless it's an emergency...but I'd classify an N- that sever as an emergency and do it if it were me. If you haven't fed them before, I'd start them out at 2 to 2-1/2 tsp Grow Big, and bump it up by 1/2 tsp each feed. I'd also go heavy on the foliar feed, at about 1 tsp/Gal. Your granulars just aren't having enough time to break down. I've also found that with the C-99 crosses I'm running (Orange x Pineapple, BCS x ST xC-99, and Chucky's Bride...they are ALL very N hungry thru the stretch! I'm battling the same problem on one of my OxP's I was trying to feed organically right now. Once you get behind in flower...it's almost impossible to get completely caught up. I'm just trying to minimize the damage!
On my next runs of these, I plan to get them loaded up really good before flipping by getting in a couple of good strong veg feeds. I'll also probably continue the Grow Big up until they get flowering really well and are past the stretch...like maybe 4 or 5 weeks in. It'll just depend on how they're responding. Best of luck to you bro! I know you'll bring her in looking great!! Best, -Max