Yes, most twig dogwoods are extremely hardy and should overwinter well in containers, provided they are of sufficient size. Generally the recommendation is to select a plant that is hardy to at least one full zone lower than your own for a permanent container planting. Both Cornus alba and sericea are hardy to zone 2, so that gives you considerable leeway in zone 6. Selecting a dwarf cultivar or stooling annually to keep growth in check (and renew stem color) may be in order, as some get to be quite large shrubs.

Thanks for the guidance!

This opens up more possiblities for winter color. The red-twigs are very attractive in a up-close display against the house or the neighbors evergreens. Now to get some larger pots and a dolly!

Gardengal is correct, of course. Anything can be grown in a container, if managed properly. But don't get so hung up on container size as a primary concern. Look at the large tree species (maples, pines, oaks, etc.) that are kept as tiny trees in tiny bonsai pots. Pay particular attention to your soil composition, fertilizer, watering practices, judicious/appropriate root and top pruning, and you can grow any plant in a container (some easier than others!).

Go over to the CONTAINER GARDENING forum and surf around; you'll get a wealth of good advice over there.

Cheers!

In zones much below 8, container size IS an overriding concern for permanent, year round outdoor plantings as smaller containers are more easily prone to freezing. And freezing of the potting media and therefore plant roots, regardless of the size pot or the cold hardiness of the plant, can be the kiss of death. Bonsai in colder climates are almost always afforded winter protection, which kind of defeats Isabella's purpose for winter color :-))