When my seed selections arrived from the Society for Pacific Coast Native Iris, I decided to follow a recently recommended method to improve my germination rate. Kathleen Sayce ran an experiment documented in volume 40, Spring 2012 edition of the SPCNI Almanac. I used a nail file or simply my fingernail, to scratch away as much of the seed coat as possible, on every seed. The seeds were placed in leakproof ziplock bags, partially filled with water, and sealed.
The bags were left at room temperature, out of direct sun (but not in darkness). The water was replaced once or twice during the month long soak- some batches of seed caused the water to discolour at first, as plant extracts leached out of any remaining seed coat.
Over the past two weeks, seeds have begun to germinate. As soon as a bag shows signs of germination, the contents are transferred to seed flats for growing on. Germination rates have greatly improved since I began using this method, sometimes verging on nearly 100% germination, when my first attempts barely reached 40% success.