Roots were visible through plastic bag on May 6th. It was time to transplant. One of the Biddy Early is growing faster than the others and will be labeled as "tall". On May 7th the Biddy Early (Tall) was transplanted in a 2 litre pot, while the other three were kept in bags. Those left in bags have had the bags topped up with soil.
Looks great.
No idea what soil that is, I'll check it out. I made my own "supersoil", though probably lacking some phosphor and maybe some trace elements like manganese, as a noob from the dense clay soil I have as a base.
My bad.