If you are talking about tall bearded iris rhizomes, I would order now online. The selection is astonishing, and you may be able to grow reblooming irises in your climate. I would buy 12 to 16 different irises- they reproduce quickly, and you can just divide the ones you like best and give away the ones you don't care for as much.

Take a look at the photo catalogs of online sellers to get some ideas. They come in almost every color and all kinds of different patterns, and some are more vigorous than others or do better in colder or warmer climates. There are lots of good sellers- you may want to order from a seller who grows near your home.

Here is a link that might be useful: Commercial Directory AIS

I agree with hosenemesis.

Bearded iris have a way of 'travelin' as they increase. 3 feet apart is a good idea, A vigorous cultivar can produce 7 babies in one year. The next year if each repeated that performance you'd have 49! Thankfully most only produce 4-5 a year.

Read the culture information on beardeds. And find out how quickly your soil drains! Beardeds do not like wet feet.

They will be planted at the top of a slight hill but the soil seems pretty orange and "rocky". I thought I would add Gypsum to help with the clay and compost (mushroom?). Anything else? Should I do a soil sample? The only thing that is planted there now is confederate jasmine (behind along a fence). Bulbs will go infront .

Top of a rise sounds great. I understand gypsum helps with certain kinds of clay. The chemistry is beyond me. But I noticed it didn't seem to do a darn thing in my adobe after a few years use.

I assumed you meant bearded iris rhizomes, not the Dutch iris bulbs. Disregard what I said about spacing if it is bulbs.

In any case, bonemeal and/or a low nitrogen fertilizer is a good thing to dig in now. In addition an inch of aged manure is a good thing to dig in now. Mushroom compost is partially peat so I have stopped using it.

Soil sample? It's not like these are rare, temperamental expensive plants. Your choice.