Should be able to take them inside, but you may get something late in
the season, to eat.
Onions continue to grow, even after picked. The green growth will not
harm you, nor will just cutting off the green and eating the rest of the
onion.

Mark Anderson wrote:

LOL. Today I pick a big tomato and go to make a tomato, onion, basil,
and chive sandwich. Not having used my onions in a while, to my
surprise, I go into the crisper section of the refrigerator to see my 3
white onions already growing -- and without any help from me! Since I
had a few extra gallon pots handy I put them all in the soil and now
they're outside.

It's pretty late in the season to start vegetables (Zone 5, Chicago).
What will happen with these and can I continue them inside when the frost
starts in October? They seemed to grow pretty well inside the
refrigerator without light. I've never grown onions before.