I'm sure like many plants, Bearded Iris perform better in full sun, but how much shade can they take? Part sun conditions okay?
I have VERY limited room and must garden in beds around my home. Because I am having some work done on my deck, the preferred bed for irises is empty now while my larger back bed, which only gets sun from around 1:15 onward, is full of irises. The plants seem more undersized this year than ever. I was noticing yesterday how hard some of them are pulling toward the sun. I have several in containers (because I have no other choice if I'm to grow them), and these get full sun. They are in superb condition. I will need to transfer them into the ground after this year, though, because they need room to grow. But they'll do ok for a season in a pot, I've found.
I have decent bloom on my plants in the back. However, if you want the plants to thrive and do as well as possible, they need more than half a day of sun IMO.
My yard has a fair number of big trees, so very little gets full day sun. After years of moving them around, the bearded iris are in the absolute sunniest place I've found. Anywhere else, they lean, and don't bloom well.
Over the years my garden at home has gotten more and more shade, and I get fewer iris bloom.
The problem with your question is that some iris will do better with less sun than other. Those are just naturally hardy, productive, iris.
In my garden Agressively Forward and Kevin's Theme do ok with mottled sun. But when I moved them to my full sun garden, they sprang up and were loaded with tall, thick stalks and big fat blooms.
I am almost ready to pull out all of the iris from my home garden because my full sun aucilliary garden (in another place) shows what good iris is supposed to look like.