Dutch Iris bulbs
Perhaps Lady Hykeaswell could instruct you on planting them.
I could use some advice being I've never planted flower bulbs before....all I know at this point is that they are to be planted during the fall season.
Thumb rule, pointy tip up, and bulbs covered with a layer of soil at least as high as the bulb itself. What I read about the Iris Hollandica is that they like to be a little deeper than that. This
link may help you a little further on Dutch bulbs.
I've never had Iris Hollandica, this lazy girl has two varieties of rhizome irises, but the thumb rule for bulbs does work mostly.