What's wrong? Phos. / Ca / Mg Deficiency? pH? Light? All the previous and more?

based on ratios of what you fed either p-tox lockign stuff out or k-deficiency. i can't do the math in my head on what you fed.. ptox would likely be anything significantly over 50-60ppm, excluding what is in the substrate to start, if soil. this is way easier to deduce in soilless LOL. but, if you can guesstimate what came with the soil this will help. K should be up around 200ppm in total relative to the volume of water that your substrate can hold at any one time plus whatever is in the soil through amendments (like above.) later in grow you'll lkely be giving everything the plant needs.. you can basically treat it like a soilless gow at that time.. after soil is sapped, get a religious 10% runoff waste water each irrigation (with fertilizer) and if you feed as low as what i mentioned above, feed every irrigation... 2x if every other is water-only. in the end it'll be the same mass of molecules fed pe day or week or month... the more frequent the fertilization, better the results, but it takes more effort, unless automated.

It's best to have a traveling pH. What I mean by that is you want your pH to get down to 6.2-.63, then let it rise up to 6.8. Once it hits 6.8, let it fall back down to 6.2-6.3. Then, over the course of four or 5 days, back up to 6.7-6.8. This traveling pH will help your plant(s) uptake any nutrients you throw at it and will help fight toxicity and lockouts. I hope this helps.

To me, it looks like potassium deficiency... but the question is "why" - and for that, I turn to your pH... it's MUCH too high! You need to get this down to about 6.2 and to do that quickly, you'll need to do a hard flush - 3x the water (ph'd of course) as pot size. You're growing in 5 gallon pots so you'll need to run 15 gallons of ph'd water through her and wait until she dries out... then give her a feed at 1/2 strength... If you don't have a pH pen, I would urge you to invest in one soonest... improper pH is one of the most frequent causes of toxicities and/or deficiencies... if the pH is not in a good range (in general, for soil, you want it to be between 6.0 and 6.5 - in flower, the range is lowered to 6.0 - 6.2) the nutrients you are supplying your grow with are not going to be absorbed. The leaves that are damaged will not recover so don't expect that... but you shouldn't see a worsening of the problem elsewhere. If you are maintaining that pH (7.4) on your OTHER plants, best to reduce it for them as well... because they will soon be showing problems if they aren't already... Good luck! She will recover nicely, believe me!

High Kalimeros, This is a potassium dificiency in the early stage. The cause of this dificiency could be pH issues or overfeeding. You can measure the pH from your soil to make sure that this is not the cause. I will explain how to do this and if the pH is in the right range then you need to flush your soil so you can start giving the right amount of nutrients again after doing this. But I will explain that after I told you how to measure pH in soil, just follow these steps. Your pH should be around 6.2. 1. Place soil sample about ¾ full in sample jar and add distilled water to cover soil. 2. Cap the jar and shake the soil vigorously a few times. 3. Let mixture stand 10 minutes to dissolve the salts in the soil. 4. Place the pH tester into the wet soil slurry. 5. Measure pH and record measurement. If the pH is in the right range then flush out the nutrients with a good flush of your soil and I will explain you how you can do that the best. You can do this flushing by slowly pour water pH 6.2 onto the top of the soil, allowing it to drain freely from the bottom of the pot. Pour slowly, so the water doesn't overflow from the top of the pot. Use approximately four times the pot's volume in water to flush the soil. For example, use 1 gallon of water for a 1 quart pot. After the flushing you need to let the soil (almost) dry out completely. From there you can start giving water with pH 6.2 and nutrients but do not exceed EC 1.8 to make sure that you don't overfeed them in their last weeks. Happy Growing! 😋