You need good garden help
You really need good garden help when you're building a garden. In this case, I needed my Japanese Iris pruned and cleaned and my friend needed some housing assistance. We made a trade. And it has worked out quite nicely. The iris are clean as a whistle and while I had to knock down his determed efforts from on top of my window (twice) he has moved to some other unknown locale successfully.
In any case, the secret to success with Japanese Iris is to use acidic soils - keep them wet/damp in the spring and early summer and then after blooming, run them a little drier. In this case, they sit on the edge of the water pond and then in July, I plant them in the general garden to dry out a bit more. I grow them pretty much in peat moss in the pot.
But you have to find your own worker.