andysays
Love and solidarity
First of all it's about economy of space and light and heat - and I figured that out long before I learned the other reasons.
Secondly you're plonking a small root system into masses of cold wet compost.
In containers it's best to build up the plant's root system yourself - perhaps better than nature.
And then we get onto using plugs instead of pots and air-pruning.
But if you're starting something in a seed tray which you're then going to pot on into small pots a few weeks later, I really don't think you save significantly on space and light and heat, or compost, and you do end up spending significantly more time. I don't use artificial light or heat, BTW, I just sow seeds in 3" pots, germinate them on a table in a sunny window, and after a few weeks or so put them in a cold frame to grow on and harden off. Hopefully by the time they've filled the pot and are ready to plant out, I'm ready to do that. It may not be the "best" method, but it works well enough for me
I've heard a little about plugs and air-pruning, and that may be something to investigate, although that will leave me with 100s of 3" pots I have no further use for.