Depends on the pot - I've got Polish Spirit in a pot 2 feet deep by 12 inches wide, and it's growing well, but will never reach it's full height and spread because it's in a pot. Any smaller and it wouldn't do well, particularly the depth of the pot is important.

I would agree. It depends on the size of the pot and how much time you have to feed and water it. Clems have big root systems and generally like to be well fed and watered. If you need to do the pot thing, use the biggest one you can and take good care of it and remember to plant it a good few inches deeper than it is in the pot you bought it in! Good luck and enjoy! p.s. there are some really good lower growing clems that do very well in a large pot if you want to have one that will stay at a reasonable height and not go shooting off! Have a look at Raymond Evison's 'Boulevard collection' and the Floridas.