Hello, I recently noticed these leaves slowly changing yellow. Mainly the main leaves and not just the bottom but higher ups as well. These are blue cheese autos in Baccto soil, I’ve rarely used ferts on it until recently, used tiger bloom at 3/4 strength every 2 or 3 watering. Water with collected rain water so I never bothered with checking ph since the growth has been incredible. I did however goof and accidentally grabbed the jug I had advanced nutrients vegetative grow ferts for my new plants and watered. Everything I’ve read says deficiencies. Now I need advice from the pros
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Without more info I’d say they are hungry for nitrogen although it doesn’t usually go that high up.
I feed with every water. 
I’d rip all the ugly ones off and give them a nice shot of N, consistently.
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How far along are your plants?
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First thing you need to do when you encounter problems are check you PH on run off, the nutes you add to water will alter the PH so this might be the issue.
Pz 
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I humbly disagree with this appreciated pro 
, Nitrogen in that advanced stage of flowering isn’t needed, I would go for Potassium instead … 
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Interesting. Unless I’m mistaken Potassium usually shows on the lower leaves. But there’s more upward spread than I’d expect too.
I’ve been known to add nitrogen in flower if I feel they need it.
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The spread is from bottoms up. But its an bad idea to add stuff before Having an good idea of the PH in the soil mix. The added nutes might cause lockouts and adding stuff would only cause more problems. Before we know that the PH is stable, we cant really suggest anything for sure.
Pz
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Nitrogen also expands from lowers first and then upwards, I have recently bought Shogun PK Warrior to avoid giving them N at this late stage so maybe you’re right and I am just trying to convince myself …
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Well they are all different and want different things at different times. They’re dynamic and that makes it fun.
Ive got a plant that is burnt up top and deficient below at the same time. Go figure.
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Normal, clean rain has a pH value of between 5.0 and 5.5 , which is slightly acidic
I think @LonelyOC gave good advice, you should check your water and runoff pH …
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I did notice the color change happened fairly evenly throughout both plants, the higher leaves changed right along with the lower ones. Yes the spots told me potassium, but the sharp even yellow says nitrogen. I agree with @Foreigner nitrogen is still important during flower, cuz as my buddy says, plants are still green during flower 
ok I’ll check ph runoff when I get home and let y’all know. I didn’t know rain water was that low ph, now I’m super curious. One other observation I noticed is the soil on the very top dries out fast and is clumpy with almost a salt sprinkled texture/shine to it. This new soil I’m trying out is very different from The usual FF. I’ll send a picture of that as well, even a root picture of that helps
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@LivingBlackSoil they are around week 2-3ish of flower. They’re autos, I dropped seeds beginning of august, didn’t write down times of them cuz they were guna be outside experiments until they needed TLC
Those green leaves have lots of N, plant starts to take them when missing and that’s why they fade out. Could be Nitrogen AND Potassium also, while checking the chart I have seen acidity won’t stop them from being both available, so maybe there’s salts accumulated and a nutrient lock.
Did you notice if that damage happened to be when you started feeding them? Autos are low feeders, maybe you should also check EC from runoff …
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@George yup they were just fine until I introduced feeding schedule. That’s what’s confusing being it looks like a deficiency, so perhaps the rainwater was off, I do use well water as well which normally is good but haven’t checked that either. I have a PPM measuring thing, it says EC too but I can’t get it to work. It’s like the digital screen skips over it or something.
So when I check run off, do I collect the very first bit of runoff? Or do I let it dump out some and then collect??? Kinda like you pee first for a bit before you pee in the drug screening cup😝
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Without having a proper PPM or EC measurer, flushing with just pHed water will come handy if you have some salts accumulation. I didn’t understand if you cannot measure EC and PPM or just EC. If you can measure ppm, just flush with distilled water or in case you haven’t, just water wit no nutes and having measured its PPM first and check results.
While measuring PPM and pH you will find out if you must keep watering without nutes or it was just unbalanced pH (which I doubt). Any case give her a good flush like you just drank five pints of beer …
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It is both. An N deficiency and, a K deficiency. Most likely caused by lockout from improper pH. Adding more nutes could possibly exasperate the issue. IME, a deficiency will occur at whatever point the lock out occurred regardless if the element is mobile or immobile. For example, K lockout occurred 2nd week of flower and affected the top half of the plant instead of the lower first. Even though K is mobile and should show on the lower leaves first. It would if was truly deficient in K, but being that it’s a lockout, it’s showing on the upper half of the plant because the plant can’t translocate the K from the lower leaves. Hence it being “locked out”, even though there is most likely adequate K in the feed or soil. The plant can’t utilize it because the improper pH makes it unavailable.
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Checking the pH runoff is the first thing I would recommend too, and go from there. You mentioned that you recently started a feeding schedule so it’s hard to think that it’s deficient in the classical sense as in, not enough being applied. I think it’s lockout either by pH out of range or by a toxicity of other nutrients from the recent feed schedule being introduced and it’s locking out absorption of critical components for optimum growth. Not just Nitrogen. Possibly excess phosphorus causing the lockouts or pH swinging is what I would guess. Hope this helps. Much love
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If hes already soaking it until run off, cant he just flush it at the same time with correctly phed water, maybe followed by the right food. Or wont that work in soil? Seems like a bad time for a hickup with autos.
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That’s very interesting what you say, so as Potassium is available in a wide pH range and always abundant in ferts and soil, a Phosphorous excess in the latest feedings (as @Sbeanonnamellow pointed) may have blocked it? 
That soil brand has limestone, which is alkaline, so it would compensate the rainwater acidity. Still don’t think it’s pH related, I would just give a generous flush with just well water, check runoff pH and ppm and go from there …
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My bad man I meant to reply to the OP of the post and noticed I replied to your comment instead, I wasn’t trying to refute what you said or anything. I hope it didn’t come across that way. I’m not sure what is actually going on with the plants OP posted but the stuff I’ve been reading a lot and listening to has me thinking about the prevalence of toxicity causing deficiency more often than I previously thought. If anyone is wondering, the channel I’m referencing is called Advancing Eco Agriculture on YouTube. They’ve been very enjoyable so far. That’s a really cool visual you just posted. Thanks for sharing it. Much love
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