Make sure your not letting the coco dry out, it will even look wet on top sometimes so it's best to go by weight of the pot. If you let it dry out it can fry the roots and the majority of the roots die/dry out and cause problems. The plant will limp along and finish with yellow/crunchy dead leaves. Once those roots die in late flower they won't regrow like in veg so sometimes you notice your pot will be heavy with water but since you root system pretty much died it can't uptake that water and will be soggy
Your plants look like mine when i was waiting to long in-between waterings, it was always later in flower when i had the dying/crunchy leave issues. by fixing that watering issue I never had any problem in coco again.
Don't think its rootboud, I've had 6ft tall bushes in 2gal of coco with no issue.
What also leads me to watering issues is that your organic soil plants are doing fine which have no problem drying out, in coco you can't let that coco get dry your roots will shrivel up and die.
You should be watering everyday maybe twice a day depending on environment ect. If you go two days without watering late in flower its too long problems will most likely issue.
I'm assuming you watering to waste? because some of these problems can actually be from overwatering if you keep the pots in saucers with no waste, its really the same problem IMO the roots die from being flooded/waterlogged from no drainage. End result is 90% of your root system dies either way.
Unfortunately you can't really fix these plants but next round just keep up with the waterings and guarantee you don't have these problems. I "battled" this problem for so long overthinking it, thinking that it was not enough mag, not enough cal, too much nutes, not enough nutes all kinds of different things when the problem all stemmed from watering issues, and a simple correction and not slacking off on watering fixed everything.
This also solved my bud rot issues, no dead leaves = no bud rot. The decaying leaves were where the bud rot always started.
Sorry I rambled on there lol.
.
Your plants look like mine when i was waiting to long in-between waterings, it was always later in flower when i had the dying/crunchy leave issues. by fixing that watering issue I never had any problem in coco again.
Don't think its rootboud, I've had 6ft tall bushes in 2gal of coco with no issue.
What also leads me to watering issues is that your organic soil plants are doing fine which have no problem drying out, in coco you can't let that coco get dry your roots will shrivel up and die.
You should be watering everyday maybe twice a day depending on environment ect. If you go two days without watering late in flower its too long problems will most likely issue.
I'm assuming you watering to waste? because some of these problems can actually be from overwatering if you keep the pots in saucers with no waste, its really the same problem IMO the roots die from being flooded/waterlogged from no drainage. End result is 90% of your root system dies either way.
Unfortunately you can't really fix these plants but next round just keep up with the waterings and guarantee you don't have these problems. I "battled" this problem for so long overthinking it, thinking that it was not enough mag, not enough cal, too much nutes, not enough nutes all kinds of different things when the problem all stemmed from watering issues, and a simple correction and not slacking off on watering fixed everything.
This also solved my bud rot issues, no dead leaves = no bud rot. The decaying leaves were where the bud rot always started.
Sorry I rambled on there lol.
.