What vine can we plant in pots that can be left out all winter?
We have a two-story building in Pepin, Wisconsin, that has a very dull south-facing wall. It currently has vinyl siding. Can we plant some sort of climbing plant in pots (there is sidewalk to the building) that can be left out all winter? Any suggestions on species and how large the container and soil specifics need to be.
Minnesota climbing vines
Sorry, but anything you put outdoors in a pot is going to die.
Here are two alternatives: move the plants to a sheltered location (where temperatures don't go much below 25 degrees) if you have such a location; or plant annual vines in your pots. Regarding the first suggestion, you can also stretch the hardiness zone a bit if you do this. However, this suggestion is the most labor intensive - moving large plants around can be hard work.
For the first suggestion, clematis, sweet pea, trumpet vine, Virginia creeper, wisteria. See here for other choices:
For the second suggestion, thunbergia, morning glory, scarlet runner bean, sweet potato vine:
As for the growing medium, we recommend good quality soilless potting mix. The pots should be sized appropriately for the final plant size, but probably pretty large. Remember that if you decide to move them into a sheltered area over winter, you will have to physically move them!