Earlier this year I decided to install some Iris 'Dark Clouds'adjacent to my 1 year old Iris 'Canyon Snow'. My experience is that Iris are hard to initially transplant and establish, but once they have taken hold in the garden they are robust. Additionally, Iris can look ratty after they bloom, but it's been my experience that if they have any strong and healthy growth, that they will survive and come back the following year.
One of my more established 'Canyon Snow' had about a 50% die back, but I wasn't too upset, since the remaining growth was strong.
Sometimes you'll see Iris planted in full sun, such as at the Air Force base in El Segundo. That's a bad idea since they tend to look terrible in full sun and the mortality rate is much higher. I've seen them in full sun in their native habitat in the Sierra, but generally there's a mountain nearby so that a full day of sun isn't really the same length of time as without the nearby mountain peak, and/or they are near a source of subterranean water. Generally they seem to do better with some shade when I've seen them in the wild and that's true in your yard as well. Mine are planted on a N facing slope with some shade from large trees.
Here's some more good information on Iris:
In Early April, 2011, Emily Green wrote in the L.A. Times,
One of the most common questions during California’s wildflower season is: “Is it too late to plant?” If you’re working from seed, yes. The lupines, clarkia, poppies and sunflowers coming into bloom now germinated last fall. It is only by the capturing of residual autumn warmth and early winter rain that they put down roots needed for a vigorous spring bloom.
However, the window to plant spring wildflowers does remain open in April for our native Pacific Coast irises. This window is kept jammed open partly by the nursery trade, which often doesn’t release the plants until March -- not ideal, but possible because irises are perennials. Although they do produce seeds, they grow from rhizomes, or tubers, that produce annual sets of roots.
If we want newly bought irises to go in the ground this year, we need to jump -- fast. Unless the weather changes, it’s still cool enough. Moreover, spring shopping affords a benefit rare among natives: the chance to see at least some of the young irises in flower on store shelves.
A year later she wrote,
Last spring I wrote about how the March release by nurseries of Pacific coast irises tempted many — myself included — to plant the flowers in April. I put up this post-script because, having done it in 2011 after a wet winter leading into what proved a cool summer, I still saw mortality rates of 15%. Anyone trying it this April would be starting after a dry winter going into what looks like it’s going to be a hot summer. Here’s the problem: If you are watering newly planted irises as they become dormant in May and June, and given the only partially charged soil, you probably will be, it’s a perfect recipe for root rot and death.
Which was apt advice for this year too, given our dry winter.