Yellow leaves

Nothing you have been "feeding" them with is an N/P/K fertilizer, and your plants are deficient in all macro nutrients it seems, but pictures taken under grow lights are next to useless for picking out details, always post pictures taken under normal white light. There are plenty of pure organic fertilizers out there that are specifically designed for cannabis growing. Bio Vega and Bio Flores made by Bio Canna and Organic Grow and Organic Bloom made by B.A.C. are two of my favourite lines and have given excellent results for years. You will need to feed them with proper nutrients very soon if you want them to produce any decent buds, what you have been giving them are just "supplements" and not complete nutrients/nutrition that will sustain your plants health, it is just the fact that the soil contained some nutrients that have been just enough to get them this far. Hope this helps, Organoman.

no nitrogen -- that isn't interveinal. soil? soilless? if soilless don't flush, just correct balance of nutes and it'll fix itself within 1-2 irrigations with propery 10-15% runoff... can hasten that with a little extra runoff, but it'll re-balance eventually and you don't have to strip anything form the substrate.. flush is for a major catastrophe occurring or you just slow it down, especially an autoflower or a photoperiod in bloom. purple? could be temperatures at night. are you drifting much below 70F? it doesn't tkae much and some genetics are simply prone to 'autumn' colors coming out. i see in the diary it's more than just senescence/temperatures though. without hving a general sense of what comes with the soil and what you've been feeding the entire time, it's pretty hard to guess as to the cause. So, looks like a Mg deficiency with interveinal chlorosis and rust spots. Could it be lock out? you'd have to eliminate that as a possibility. In soilless you need about 100ppm of Mg concentration with RO water (assuming a 20ppm uptick from my hard water tap)... Now in your soil it may already have some etc etc.. it's possible you are locking out Mg with Ca... just a thought... try using magnesium sulfate (can use food grade epsome salt -- it will have the guarnateed analysis labels -- instead of cal-mag for this. You still need to add some calcium if it is not included in your other fertilizers at appropriate levels. other consideration here is how uch S you add elsewhere... soil is a balance.. gonna have to learn it.. .soilless is science and can hit ground running using existing knowldge and readily available nutes etc etc. can still apply some of the 'science' to soil grows, but you just widen the give or take range a bit further while you find that balance. it's still good to know what oyu feed in ppm of each molecule so that when these problems arise you ahve good information at your fingertips... and soon enough these problems should never occur... i rarely see a nute issue in last nearly 3 years since switching to a professional Ag brand like jr peters. i've even used it on some soil grows with FFOF mixed with extra perlite that turned out fine. it's just too difficult to diagnose with many unkowns... pick a path and move slowly.. hope for the best. always easier to add things than remove.. so becareful if ramping up.

I think it’s NPK! All of the above. Give them a low dose of all.

Best thing you do is rinse her with ph water and start again with the proper nutrients for her age. Just incase there's any lock out , Good luck 👍

In my opinion, it seems like over-fertilization since the tips of the leaves are burnt. This can cause a blockage in the ability to absorb nutrients, leading the plant to generate deficiencies in other elements. Recommendation: Apply a watering only with water, 2-3 liters (depending on the size of the pot) with 260ppm and pH= 6.3. With that amount of water, it will definitely drain a bit, then measure the ppm and pH of the drainage water, and if the ppm is too high, you should lower the amount of fertilizer; if it's too low, you should increase it, and the same goes for the pH. I don't think it's a nitrogen deficiency; the plant in flowering doesn't require much nitrogen to generate a deficiency. Your grow looks super good! I hope to see the recovery! 💪💪