Can't remember how mine was potted when I got it(another member dug it, and I got it at our club auction), but it is in a typical soil mix in a pond basket. But now that we talk, it may not be the best situation as it didn't put on much growth last year, at least not what I expected, so I may need to work on it to amend the soil. Just a plain basket lets it dry quicker too, what I usually do is to double the pond baskets, it keeps the air pruning, but the second layer keeps out the wind a bit, I suspect.