Has anyone overwintered madasgascar periwinkle through the winter.

It is listed as an annual here but I don't see any for sale most years.

I found one this year and have rooted some from the plantings at work. I suspect landscapers may be buying the bulk of them and that is why I don't see any for sale.

I did not realize they were perennials in warmer zones until recently.

The lowest temperature listed for them was 41 to 45 degrees F. I thought I might try them in my unheated greenhouse that covers the pond this winter. I have had cannas keep some green leaves all winter, as well as some of the bog and water garden plants. I could also bag the pots and set them in the pond, since the water stays about 50 degrees all winter.