Nice looking plants ALX.
I noticed you already have your plants by the window. I still have mine under a light 16hrs a day on a heated blanket. I have read that giving them direct sunlight when very young can cause them to become spindly. From the picture it looks like your tray of smallest plants has become slightly spindly. Some of my plants have become spindly because I had the light up way too high and blanket warmth up too much. Ok, now the question (finally).
When you transplant to larger containers I assume you bury part of the stalk underground. Do you ever have trouble with them properly rooting afterwards?
I'm wondering because I have some black brandywine and cherokee purple that are very spindly and I would love to not waste the seeds, time and effort. I still have enough time to start new ones and will try transplanting before I do anything, but was just seeking your opinion on the matter.
Here are my ones that are more "spindly"
As you can see I will have to bury them kind of deep.
My little grow area...
Under the towels are another tray of tomatoes and my hot peppers. I accidentally killed my first ones, too much heat and not enough water-oops.
One more question, sorry-
Do you germinate the whole time without covering them from the light? I was going to but haven't, but you plants seemed to germinate fine so I was wondering.
Sorry for a rather long post, thanks for any help.
Good luck with the garden