Abstract: The seeds of Iris ensata, Iris setosa, Iris chrysographes, and Iris bulleyana (the four species of Apogon Iris), all exhibit dormancy, but the germination varies from species to species. We researched the hygroscopicity of Iris seeds, different scarification treatments, the mechanical resistance to embryo growth (by Instron 5848 MicroTester), the growth potential of the embryo (by placing excised embryos in osmotica of PEG-6000), and cold stratification treatment. The growth potentials of the embryos were not enough to break the mechanical resistances of the micropylar structure and this was the main reason why Iris seeds failed to germinate. Excised embryos had 100% germination and the seedlings grew well, that is, the excised embryos were not dormant. Proper scarification, especially the removal of endosperm at the micropylar end broke dormancy. Cold stratification or exogenous GA treatment alone also greatly promoted germination. In summary, the four species of Iris seeds conformed to non-deep physiological dormancy.