Years ago, I had grown several varieties that had always wintered without problem here in my zone 3, these plants had been situated in full sun and good garden soil.

There are a lot of species of Tradescantia, not all of which are hardy, but for the hardy ones you shouldn't need to do anything special to overwinter them in zone 3. I have an unnamed light blue one. They like moist soil.

I have no trouble over wintering them Violet-blue, rose. white,and a light blue are colours I have . have become invasive at timesbut still enjoy them