Casey - I frequently get "vertical" rhizomes, too, and am never sure how to deal with them. Plant them so the rhizome is parallel to the ground level but the leaves stick straight back? or plant them vertically so the leaves stand up straight? I've followed the latter approach, but doubtless I lose some of the increases that get buried.
I think your idea of using soilless mix for the top 3" is brilliant, by the way. I shall keep it in mind for next year.
