I'm not sure I have ever noticed any that seems to last longer than another. Things can vary just from year to year. Maybe I should start tracking mine. I know Jurassic Park started blooming here on April 18 & still blooming very nicely, but it is a very large clump. Kevin's Theme is a similar looking iris that has not started blooming yet.You can go to an web site that sells iris, Schreiners or Blue j iris. In their descriptions of the iris, they tell you if it blooms extra early, late, etc.

Thank you. I'll try to find some that can bloom at different times.

Short ones tend to bloom earlier, so move through the sizes.

There are those that bloom twice a year. Wayside Gardens has great ones.