For many years I have had Siberian iris in my garden. They are very easy to grow, their late spring blossoms are very attractive, and they multiply almost to the point of being invasive. They are currently blooming in many areas of my garden.
My mother used to grow the traditional German bearded iris that are so showy and beautiful. She use to call them "flags". Quite a few years ago I tried planting a bearded iris, but the next year it did not come up. I found out later what I had done wrong. The bulb-like roots called rhizomes must not be buried; they must be exposed to the air. If the rhizomes are covered they will rot.
Last year a friend gave me a bearded iris. I planted it and left the rhizomes exposed. This spring when I returned from Mexico I found that, in spite of our sub-zero "polar vortex" last winter, the iris had sprouted and was full of buds. It has now started to bloom.
Now that I know that I can successfully grow them, I have purchased a couple more German bearded iris to plant in the garden.