In http://gardening.stackexchange.com/a/421/138, the answer mentions "Remember to harden off any indoor plants for a few days before transferring them outdoors." I assume this is something you would need to do to help them survive in the colder, more variable climate outside. We're trying to grow tomatoes and peppers, both of which are supposed to be started indoors if I understand correctly.
How do I do that?
For what it's worth, we live in central Minnesota, so that's the climate they'll be moving out into.