Clematis: jackmanii "growth year" advice needed!, 1 by koshki

koshki wrote:
My new jackmanii 'Superba' arrived yesterday...in a quart pot, and I think it looks fairly healthy. I have not yet decanted it to check the roots, but it has two growing stems and I think two more eyes that are about to get started.

I have decided that it needs a "growth year" in a container, but have a couple questions for all you clematis gurus out there.

First, is a gallon pot appropriate? Narrow and tall, rather than wide and squat? Glazed rather than terra cotta?

What kind of medium would you use? I have decided to use Al (tapla's) container mix recipe for the rest of my pots...would that make sense here? Amendments?

Should I trim this down? Pinch the growths? Leave it alone? How deep should I plant it?

I plant on putting the container right in the spot where I would plant it next year, to make sure the spot is good for it.

Any other questions I have neglected to ask that I should have asked?

TIA
Katherine