In trades I received quite a few seeds for bulbous plants this year, including fritillaria, zephyra, etc. Although most of the seedlings looked good immediately after germinating, many have gradually begun to yellow. I don't think it's damping off, because the yellowing usually starts at the tips and works its way gradually downward.

I did put the types which preferred dry conditions in cactus potting soil that wasn't sterile, but the fritillarias were in regular seed-starting mix and the same thing seems to be happening to them. Anybody have any ideas? It's way too soon for them to be going into dormancy!