all of my mini's are in containers and even they do fairly well surviving minus 20 celsius with no real special protection. they should do even better in the ground .

Minis are tough. Some of them will survive whatever winter throws at them with no problem. Some others appreciate a little protection in winter. Especially in their first winter I think it would be wise to cover them with some mulch (just 4-6 inches is fine).

I haven't lost any yet... and I only throw about 3 or 4 inches of mulch around them... although, I did have a beautiful unnamed red die back to the ground as a result of this past winter. It's making a valiant comeback, though! I'm in the Champaign, IL area.

Most of my minis are from Heirloom Roses, though a few are just inexpensive generic minis pulled off sale tables after Mother's Day, and planted in the gardens.

I do have an order coming in from Nor'East... so we'll see how those do. I expect them to do the same as all my others... thrive!

I purchased some miniatures in a Valentine's basket. I've been trying to get them identified, in part to find out how hardy they are. The suggested varieties are all zone 4/5. That isn't hardy in zone 3a.

Any ideas for keeping these alive through the winter? I'll kill them off if I bring them indoors (mites, mildew, etc.)

I'd try burying them in mulch sometime in the late fall after they've gone dormant and uncover them in the spring. Also, planting them near the south side of the house can make quite a difference.