I'd have to call Claudia Barton Blair a luminata plicata. That's a mouthful.
Leslie, I usually separate my Japanese every two years. Since Chad Harris says the rhizomes grow up I was thinking of adding more potting soil to my two year pots. I have two pots of each so it may be time for an experiment.
I grow my Japanese iris in a lined shallow box filled with water. I take them out for the winter. I leave my I laevigata albopurpurea 'Cholchesterensis' (another mouthful) in the water all year.
