You are getting stem rot, it is the only real danger growing this stuff. You must keep the seedlings dry use well drained soil with lots of sand. I water from the bottom, I.e. Put the pots in water ab
and don't sprinkle the tops. After about the third set of leaves, you can't kill them, dry. Wet hot cold, you won't have an isseu. Only other problem is they don't transplant well.