I have been lurking and reading about all the work you are doing to
grow iris. We have lived in a variety of areas from high mountain
deserts to lowlands where winters were as cold as 25 below to 29
above.We never have bothered with soaking or refrigerating seeds. No
matter where we lived we germinated our seed simply by letting the seed
shrivel and shrink until about November/December. We then plant the dry
seed in potting soil in pots. Placing a little gravel in the bottom to
assist drainage, add the moist soil, push the seed in slightly and top
with 1/2" pea gravel. The top gravel prevents frost heaving. The pots
are then set out on plastic or sometimes a raised area and turned over
to mother nature. In very dry areas one must add some water
occasionally. Klamath Falls has about 8 months of winter weather and
can have a freeze any month. Yet we successfully germinated 1300 seeds
Hope this may help. And yes, we have very good germination.
Maybe Mother Nature knows best? You might give it a try.