"Billy" wrote

I was wondering if anyone else had the same observation as I have.
I use a soil that is specifically for germination (high sphagnum
moss content I think) and it seems to do a good job of germination
but then the seedlings seem to lack vigor. When I transplant the
seedlings into larger vessels with "regular" potting mix, the
plants suddenly become vigorous.

Anyone else have this experience?

Exactly!

The starter I used, Magik-Moss Seed Starter is excellent, as far as
composition, water retention and working form, but it seemingly has the
nutritional value of shredded plastic. Next year I'll mix a couple of cups
of alfalfa meal and a little bone meal with each bucket. That should green
things up, as compared to the pale starts I was constantly chasing with
nitrogen this year.

Steve Young