Are these Siberian or Japanese??

Thanks Susan. It's a Japanese. A pleasant surprise since it rained most every day during bloom last year.

Does it need a lot of water? I hear they are heavy feeders, what do you use for fertilizer?

I'm not sure what I do is a good guide as I've only been growing for a few years. Per Polly's recommendation I fertilized in September when they're setting flower buds. I used a balanced time release, heavily. In early spring I pulled mulch back and applied composted cow manure, heavily, then re-covered w/mulch. Balanced fertilizer, per recommendations, early June. Being in New England I have acid soil and our Spring was fairly wet so supplemental watering was minimal, but more than 1" per week.

Edit: Check out "CULTURE FOR JAPANESE, BOG, WATER AND SPECIES BEARDLESS IRISES"
Irises (Iris)

As you're in z8 this is good thread where Polly and Charleen are testing JI bloom in warmer areas:
The thread "Japanese Iris" in Irises forum