what about the small pots they are in? will repotting slow the flowering process by much?
This is definitely nute burn, I had the identical symptoms during a recent grow on a very nute sensitive blueberry plant. Stick to a Feed-Water-Water-Feed schedule, making sure that each time you water you are getting about 20 percent runoff. I have found that feeding more frequently than this always leads to lockout at some point. This becomes a self-regulating method because the two waterings between feedings will flush out accumulated salts. If you are feeding as much as you are, the nutes will just keep building up, messing with your ph, and reacting with each other in the soil precipitating into unusable salts.
As for repotting, I had to do this once at about week 3 or 4 or flowering. What I found at the end of the grow, was that the roots never really grew much after I had re-potted. I think most of the root growth that happens over the flowering period takes place during the first few weeks. Basically once the plant stops its flowering stretch, it stops its major root growth as well.
As it happened, the plants completely stopped progressing for about a week, and I ended up having to extend my flowering time by an additional 14 days before they had ripened properly. Ultimately, repotting was basically like putting my grow on pause for 2 weeks. In the end, the one plant that I didn't bother to re-pot ended up outperforming the others, even being completely root bound.
This is just my personal experience, others may have more luck re-potting in flowering, but I won't do it again. Of course, I learned my lesson and now I re-pot two weeks before I flip to 12-12. This allows time for the plants to adjust and grow roots into the fresh soil. If the plant has to divert energy into growing root mass, it is going to detract from your flower production significantly, so you want it complete by the time you go into flowering.
