I started using Coco after a ten year hiatus from growing. I was always in Sushine mix before. I just ruined two crops of Auto's, and here is what I did wrong. Coco is NOT soil. Coco is pure hydroponics. Even after massive research, I was fooled by old thought patterns. You look at it, and you brain thinks ' Wow, looks like really clean, consistant soil, or soless mix'. Which it is, but with ZERO nutrients. Think hydroten. Seriously. Even if, and this is really not necessarily smart, even if you supplement coco with humus, or other amendments. What I did wrong was that I starved my babies severaly in the first couple of weeks in pure coco. Now, there is sufficient nutrients in the cotyledons to keep seedlings alive that long, but no enough for them to prosper. To vigorously GROW ROOTS. The second crop, which is 6 weeks on, and is going by the wayside now, has the root structures of a two week old plant. I have kept them alive, and fairly healthy, by foliar feeding to this point.
What I am going to do now, with the new babies, is feed every watering, which is going to be everyday in a couple of weeks. As soon as they have sufficient root structure to dry out the coco quickly. Additionally, I recommend loading the coco with ph balanced nutrients at the seedling level just prior to placing the split seed in to it.
Boy - is there a lot of crappy advice about coco on the inter-web. There is about everything, but coco even more. I finally was able to separate the hobby growers posting from the pros. And the pros say, feed every watering, but very small amounts. Better yet, drip irrigation on timers. I'm using G.H.'s basic set of gro, bloom and micro. Take what the bottle says for seedlings, and cut it in half. Or one thrid. And then slowly increase. I have an EC metter coming in a week or ten days, and then I will be checking PPM going in, and PPM going out. This is the only way to tell if your kids are eating their spinach, and if you are giving them too much to eat at a sitting.
How this might help even one person from jumping through the hoops I did.
Pease. Stay safe, stay happy.