There was no need to chop at all! That is nothing to do with light bleaching, or as someone mentioned, sulfur deficiency! That was your main cola, it was closest to the light, so
it grew the hardest and thus, taking some extra nutes from the leaves to maintain its stronger growth. By chopping it, you killed it, what's the point to chop something that still has at least 2 weeks to go? You won't get any potency from it anyways, might as well give it to the squirrels! When you see posts like this, 'ph is fucked up', you have to learn that these are cluless people taking wild stabs in the dark with no info to back their 'advice' lol...you follow blind advice like that, and you end up like you did, with a chopped main cola that is now useless to smoke, use it for butter.
I've grown in miracle gro as well, with slow release nutes..the plants grew amazingly! One has to understand how plants grow and how to feed them what and how much! A successful grower can grow in sand with few amendments! This myth of miracle gro being a disaster is just that, folklore! Most people can't grow a cactus here, so they will look to blame anything and everything for the failure of a crop..it's not the dirt stunting the plants, it's that most people have very little knowledge about plant growth and the science behind it!