I have a single plant with two leaves with the same pattern what type of deficiency does this look like. Grand daddy purple photo. Full canna coco line except boost, cal mag and silica.
Starting of iron deficiency. Need to check the followingg: 1) is pH climbing up? 2) Is there too much P, 3) wet soil? even if plant can tolerate water logging, iron turn in to rust and won't get into the plant.
Spraying iron sulfate helps. Feeding more iron will not help. And soil and feeding need to be correct.
Cannabis does this from time to time and for reason at all. I believe it is chlorophyll related, and is not nutrient related or pH related and will not affect growth, potency or cause any other health issues.
Hope this helps, Organoman.