I'm in zone 6 also - maybe 6b, northern Virginia near DC.
I sell extras and pot them up and there are often some left over at the end of the year.
To be most certain, sinking the pots into the ground is probably best (some insulation for the roots). I've also had an excellent survival rate just setting the pots on the soil in my raised beds or even leaving them on the upside down carpeting which we use to suppress weeds in the pathways. I feel as though contact with the ground may provide enough moisture to keep them happy - not sure about that however.
You could also pile all the fallen leaves available around them for further insulation. I suggest a couple of pots of each of the ones you don't want to lose .. just for backup.
Best of luck with your daylilies and your upcoming move.
