Same as for other roses, we say a "minimum" of 6 hours per day during the main growing season. They can sometimes get by with a little less, but they might not bloom as well or grow as tall.

Is that also true for hot Arizona? I just moved mine into lesser sun. So they need more? They did better in my backyard as opposed to a porch with morning sun. I thought maybe they were getting too much sun! They looked stressed and so I increased water, but didn't seem to get better, & my gerbera is a lush green foliage but no glowers coming out when they have in the past. I've been ill from valley fever & can't remember for sure if a certain time of the year, but otherwise seemed to be fairly consistent except in the few months of cold.

In your climate, morning sun is probably best and then dappled shade later. I have roses on the east side of my house and they get morning sun, but are in shade in the afternoon and they do well.