One pot is what I would do. As small a pot as all of them would fit in for over the Winter only.. You will be able to water more as you will have more roots in a small area. In the Spring definitely separate for going in the ground about 6-8' apart. the colder your zone you could bring them in a little closer as they will not have the time to get gigantic. I am in zone 7-B justB. When you dig it up, post a picture and let us check it out to see if you may need to cut it into two pieces.
