I never get them anywhere near the thickness of a pencil, but they are tough little guys, probably the toughest of all the seedlings I transplant. They don't tend to wilt or anything. My cell packs went out to a cold frame several weeks ago and I transplanted them today... approx 3" and as thick as... a pencil lead? Results have always been satisfactory, over the last several years.

One wrinkle is that they can be planted deeply, with just an inch of green showing. I think that would tend to reduce the trauma... but you were going to harden them off anyhow, right? What if you start on that after they've had a few days to recover from the repotting? You know, sheltered from wind, filtered sun, gradually increase exposure to both??

That said, I've had a hard time this year with seedlings in general & part of it is that here in the NE we have had lots of snow and cold this year, with the occasional hot day thrown in. So my warm season seedlings sat indoors too long, and then went out on the hot days... The cool season crops, including the leeks, have been hanging out in the cold frames and are fine.

by the way I am growing 'multiplants' for the second year -- four seedlings per cell, but then planted on a 2x wide spacing in both directions. It seems to work...

best wishes

Thank you so much for your response. I've been worrying over them! I will follow your advice. Beth