Partial shade to sun. I lost it when the rose it was planted under got too big and shaded it out.

I have no full, blazing all day sun, and I suspect it would be fine in the sunniest place I have. I've got a lot of a related iris, I. tectorum, and that can handle as much sun as I can give it.

As for moisture, I think we get a lot more rain than you do, so I don't have a feel for its drought tolerance.

I have a very large clump of I. cristata that has done very well (and blooms profusely) in an east-facing border that gets about 4-5 hours of direct morning sun and then shade for the rest of the day. The soil there is consistently moist (on the verge of boggy after rain).

In the wild, they’re a denizen of moist, shady woodlands, so I definitely wouldn’t put them in a hot/dry location, but they can definitely handle more sun with consistent moisture.

Also make sure you plant them with the rhizomes at or slightly above the soil surface (like you would with bearded iris). Here’s a photo of my patch at full bloom from earlier this week:

Mine are in a spot that is relatively shady and are fine, though not as dense as the photo above. They are on the edge of native woods in acid fine sandy loam and never get supplemental water.