I always get a lot of seedlings that have been through that,
simply because I run out of room indoors under the fluorescent
lights after potting up from seed-starting cells to newspaper
pots. Most of them end up outside in these things for several
weeks before transplant:
http://www.greenfingers.com/images/s...Greenhouse.jpg
(With an incandescent light bulb in the bottom in a shop light
fixture like this:
http://www.google.com/products/catal...wAQ#ps-sellers
to keep it above freezing at night. My seedlings actually get
quite a bit more hours of cold temperatures than what Ami's
post described, with many nights in the 40s F.)