Has anyone found a source for lists of shrubs and trees that are hardy when container- grown outdoors year round?
Our driveway (no garage) was put in next to the sunny south side of an addition just before we bought our house 27 yrs ago. The driveway extends to the house foundation, leaving no dirt strip on that side, so we had constructed 4 large cedar-(then painted) boxes, about 28" H x 36"W x 24" D , which are up against the clapboard house on either side of the driveway door into the house. We have had great success with chamaecyparis nana lutea, variegated box and sedum in those boxes. This year I have added clematis and campsis- trumpet vine. I have a friend who has a mature planting of a red twig dogwood shrub in a whiskey barrel up against her house. Any other shrubs or trees we could add to this list? She and I do nothing to further protect these woodies- no teepies or wrapping or snow mounding, though mine have snow cover most years.

I keep thinking there must be a book or magazine article with lists of candidates; so many people need this info!
Thx much.

Here is a link that might be useful: cotton-arbo retum; free; open to the public