Well fortunately bearded iris don't need all the mulch and prep that the water iris require. And yours have already proven to be adaptable to your rocky soil. As long as they have soil that drains well and a feeding of fertilizer a month or so before bloom and again during the dormant period they will probably be happy. The most basic of fertilizer is to use 8-10-10 or good old bone meal. Spread it around the plant so the roots get fed, but don't let it get on the rhizome because it can cause the rhizome to rot.
Your climate is less humid than here, so I am guessing you have hot days and cool nights? You should be able to transplant the iris in late August. I don't think you want to wait until September if it starts getting very cold at night. You need time for the roots to establish themselves before any frost. If you want to help out your roses now, you can always dig up the iris if blooming has ended and either put them in a new space or in pots until you have a new home for them ready. It is not ideal, but .....
Did they bloom at the top of your slope? if so, you could always put them back in that area if you don't mind their shorter height.

I know there are some other Cali iris folks in this forum that could give you some good feedback too.

Leslie ...

Thank you for taking the time to answer my question. I appreciate it very much.

I really don't want to wait until August or September because I want to use the sites where they are currently located to plant more appropriate plants. Their current siting was just one of many of my novice mistakes.

The reason I moved them down from the top of the slope was that I couldn't see them ...

These plants are true survivors. The previous owner of my home was in her 90s when I bought the house and had probably not been on the top of the slope for a couple of decades. I've never fed them. I did know enough not to cover the rhizomes. They keep coming back very well every year. My rocky soil has perfect drainage for almost every plant, but it's hard to work in to create beds.

They are pretty plants, I just have them sited in the wrong spots.

Smiles,
Lyn