Propagation: Coconut coir stunted growth, yellow seedlings??, 1 by Rookerie

Rookerie wrote:
I use coir as well, and normally have good luck with it.
I never have damping off problems, and it's very easy to use, to water, and from which to re-pot seedlings. The *only* problem I might see are gnats, and when they become evident, I back off on the watering and add Bt Thuringiensis. Problem solved.

However, this year I am seeing the same problems as originally posted (in 2010) by dlbailey: "The leaves are yellowing and the stacks are purple." Specifically on my tomato and pepper seedlings.

Most of this year's seedling are already out in the garden beds and doing well. The only ones left are the tomato & pepper seedlings, a few amaranth, cabbage, and swiss chard (all from Baker's Creek.)
None of these seemed mature enough to take out with everyone else.

However, I DID pot them up into "garden" soil (the name escapes me, but it's a very peaty, enriched mix) Still, weeks later, nothing seems to be actively growing! There are no additional leaves on any of those mentioned. In fact, several of the amaranth in the same pot have died, leaving only one or two seedlings.

I've fertilized with a weak solution of Alaskan fish fertilizer. Still no change.
I'm beginning to think I need to take them out and place them (still in their trays) on the garden beds for....I don't know....revitalization? :) Even though they get plenty of sun in the greenhouse, they act like weak shut-ins!

(The included photo is btwn potting up all seedlings and taking some out to the garden)

Suggestions?