Coco is a hard thing to start out with. Its my 3rd grow and I still wont go near it yet lol. Especially with an auto. PH needs to be PERFECT, nutes perfect. Coco needs to be flushed alot as well (so i have been told).
Those plants are pretty much stunted now, but just flush them out real well with plain water PHd properly. Go get some Advanced Nutrients PH Perfect. Do 1/2 strength dose of it. It works wonders to bring back a unhealthy plant due to ph or deficiency issues. I used to grow organically and had so much trouble with PH, especially in flower. Now with the PH Perfect i havent had an issue, and i am running 14 different strains, autos and photos.
If you want to use coco, start with a soil/coco mix (aka SeaSoil.com) or something like that. Ittl help give u a bt of breathing room when it comes to learning PH lol. It seems to be the rampant monster for an indoor grow lol. I was always using PH meters and test strips, Up and Down additives, PPM levels. And still i had problems keeping PH down. Im not plugging the Advanced Nutrients products or anything, they just seem IMO to be some sort of miracle of cannabis growing. I use Sensi system A+B, but they have the Connosieur and 3 part micro system too. Ill be trying the 3 part next grow. I havent even TRIED theyre bud additives or anything but the base nutes so far and I bet there will be a big difference on my next grow when i use the extra's. Im kinda doing a NO-NO rite now due to lack of funds. I mix a 1/2 to 3/4 strength PH perfect, and add some ORGANIC blooming nutes (BioThrive Bloom) to it. Im pretty sure its not reccomended, and i wont recommend it lol, but its working for me. Oh ya and dont forget the CalMag.
Good luck on your babies, i am thinking of ordering a blue mystic for next time too, Check out my 14 strain grow....
https://www.rollitup.org/indoor-growing/748887-multi-strain-grow-600w-15-a.html (White Widow, Purple Kush, Bubblegummer, Acapulco Gold, Think Different, Super Lemon Haze, Chocolope Kush, Romulan Diesel, Strawberry-Blue, Viking Blueberry, Sweet Afghani Delicious, Critical Hog, U-Pink Kush)
I tried FFOF and it sucks, its real expensive, burnt my plants immediately pretty much and they never did recover and got worse with every watering, its way too `HOT` of a soil. The reviews i have read people either love it or hate it, seems to be no in between. Seems like poor quality control to me..........
Especially for autos. If u want easy, use plain Perlite (30%) 40% peat based soil product(eg. ProMix), and the rest worm casting, bat guano, oceanéfish compost etc. Just bottled or filtered water for the first 3 weeks, then light fertilizer doses with rain water or PH`d tap water. Stay away from manure type fertilizers they have too much nitrogen and ph can fluctuate alot in them as they are mass produced to the max and no quality control.