I'm one of those rare birds, that thinks this whole 'lucas formula' idea is a load of crap (don't take my word for it, read the ingredients, of your 3-part formulas, you will see, leaving out Part One, not only lessens the nitrogen, but also leaves out important micronutrients and minerals) ... don't concern yourself with available nitrogen in flower (in my opinion) ... and, most importantly, ignore the color of the pistils (hairs), that does not give a true reading of maturity ... harvest according to the color of the trichomes, and only, the trichomes ... LOTS of trichome postings in here, can be found with the 'Search' function ... happy gardening :thumbsup: