keep soil damp not wet do not let it dry out untill germination

I had some lettuce volunteer very early in spring (I should be able to eat it shortly), as long as you have regular rain it should come up on its own. Don't let it dry out if it's in a planter...

In your zone and in an uninsulated container, I would imagine the seeds froze. The embryo cells would then have ruptured when it thawed killing the seed. I honestly doubt you'll get any germination. But yes, if you want to continue the experiment, keep the soil moist but not wet.

Once the soil temp in the container is consistently up to 40 you should see germination with 10-14 days. If not then it's time to move on. ;)

Dave