Which dwarf evergreen? Not all are created equal and some are not suitable for pots year round in zone 5. Where you are in zone 5 may also matter.

tj

I would expand tj's statement to most dwarf conifers are not suitable for year round container culture in zone 5. We need more specifics.

I live in central PA, zone 5. I was thinking a dwarf Alberta spruce in a pot.

That is a selection you can get away with growing in a container in a colder zone! How large a container to start with will depend on the size of your DAS when you get it. The plant should be proportional to the size of the container so not too big nor not too small. The rule of thumb is a pot that is 2-3 inches in diameter wider than the rootball. Depth is less critical but again, needs to be in proportion to the size of the plant. And you may need to up pot or increase the size of the container as your tree grows.

Make sure your container itself is able to withstand freezing weather. And pick a high quality bark based potting soil. The larger the soil mass surrounding the roots, the better the tree will withstand the winter cold, so don't start out too small with either the tree or the pot.

This link may be helpful: https://www.gardenweb.com/discussions/1389927/trees-in-containers-iii#n=236

Thank you?