The Tale Of Two Seedlings

[AustinA]

Wanted to get some input on these two seedlings. I didn't know what I was doing, so I seeded directly into Hydroton. Sweet peas took off, and one of four spinach sites look good. There are only one or two roots on the other spinach plants. Just want to verify that this is just a matter of seedlings not taking. I am new to this and trying to figure out what went wrong.

Stats: Direct seeded into Hydroton inside RainForest 36.
Three weeks old, no nutrients until seedlings sprouted, then very diluted.