Are they recommended for your zone?

They are hardy to zone 5 and are typically planted in fall with the other spring blooming bulbs. And like them, they require very good drainage and lots of sun. In milder climates, they will produce foliage in fall and flowers in midspring. In colder climates you may not see any growth of foliage until early spring as well. Other than that, they are not at all fussy and should bloom without issue, however I have found them not to perennialize (return reliably) very well and are best replanted annually, much like most tulips.

I've planted many Dutch iris several years ago. They bloomed a year or 2, but only 1 clump of yellow ones have lingered. Only a couple of those bloomed last year, I imagine mine need to be divided.

Mine come back better if I plant them about 8 inches deep.