I only have I. germanica and Crimson King that both grow and increase prolifically (sp?). A friend brings lots of Frank Adams to our iris sale every year so it must increase well here in KY. I. germanica seems to be very rugged and never seems to have rot or even leaf spot. I have several clumps of it in the worst soil and varied conditions of light and it keeps trucking along and increasing nicely as well as blooming every year.
