In article , Kay
writes
Not if the plastic bag is not clear - some seeds are likely to germinate
earlier, and they'd need light. There's also more chance of damping off
if you leave them in sealed conditions.

I thought he was talking about pre-germination? Is there a problem with
leaving them in the bag while they haven't germinated?

Some seeds require light for germination, but apart from that, in a
slow-germinating batch of seeds germination is likely to spread over a
fair amount of time - so depending on when he removes the bag either
half the seeds haven't germinated yet, or the other half have produced
etiolated seedlings. A clear bag or a mini-cloche should be OK.
--
Stewart Robert Hinsley