I thought I should look up when to transplant the lovely little mystery seedlings that volunteered to grow even after I forgot to label them. They're the littlest ones in this picture:
So, I googled, clicked on the 1st handy result and found this: http://ag.arizona.edu/pubs/garden/mg/propagation/transplanting.html which has this important bit:
"The ideal time to transplant young seedlings is when they are small and there is little danger from setback. This is usually about the time the first true leaves appear above or between the cotyledon leaves (the cotyledons or seed leaves are the first leaves the seedling produces)"
This was okay news for the little ones, but notice the big one in the yogurt container? Yeah, that's the beans I planted to see if they'd grow, and grow they did. I was thinking (wrongly) that I shouldn't try to put them in a pot until they were nearly root bound. Big Mistake! Here's how big they are (shown on about a 12" shelf height):
I'll have to transplant them today of course, and hope for the best!