Sadly, it's not meant to.

They might be advertised as such, but are not cold hardy for you. I tried, too, and at the time (about 10 years ago) I was in zone 5b, but now we are 6a. I might have a fighting chance to get it to come back from the roots, but Maine winters are just too long and cold, sorry to say. (I am in coastal Northern MA.)

Here is my frosty foliaged one. The photo was taken two weeks ago mid day, so I apologize for the overexposure and the overall air of neglect.

I like the foliage on this one; does it get blemishes like the dogwood in summer? I had sunshine blue and think it’s gold foliage with the blue is nice; unfortunately it died.

No foliage blemishes on mine.

I looked at old order forms on line, and of the two green leafed cultivars I can find info on, this is more likely to be Caryopteris Dark Knight.

Years ago, I got one at, I think one of the Connecticut plant swaps. It survived, and has given me several children. At this point, I don't even consider them marginal. They die back a bit, but always come back.

Spring planted, on a slope of hard, unamended alkaline clay soil.

I successfully grow Sunshine Blue, White Surprise and Summer Sorbet and have never had winter hardiness issues. Last year I planted three Lil Miss Sunshine in late spring. One didn't make it to winter, one didn't make it through winter and one came through winter and died later. It was very wet here last summer, fall and this spring so that may have had something to do with it but going forward I will avoid that cultivar.

I agree that early planting and good drainage may help your success rate.

From my experience, Sunshine Blue II is the hardiest / longest lived. Pink flowered varieties are the least hardy. Agree with others that you should plant in the spring or summer only and the soil needs to be well drained, especially in the winter. Trim back in the spring after growth starts.