I've taken the plunge and ordered/received a couple dozen cultivars of TB iris this year...for the first time. The others of this type that I've worked with previously were mostly shares of plants that were here already; likely ones that are nigh unkillable. I'm wondering why, if rot is such a big issue with a lot of these plants, aren't they seen more often mulched beneath with rock? Most garden images I see show bare dirt. I did see a stunning picture of gardens mulched with rock at one of the suppliers I purchased from, but it seems to be one of the few.

Any thoughts on whether or not I should do this would be greatly appreciated.

As you say, I have seen it done....especially with the AB's.....and, in theory, anyway, it should work. Rhizome part way buried in the gravel, and the roots in the underlying soil.

I have never seen that done, but rock mulch would help with erosion from heavy rains. Hmmmmm.

The area where most people have grass/lawn I have rock mulch. Snakes do not like to be in exposed areas, it is great on erosion control, I like the way it looks and I never mow. Have not cranked my mower in two years. Most of my irises grow in beds with borders of brick, timbers or blocks but this year I have planted a row of noids in the stones. I am going to see how that works. Also, the leaf blower works much better when there is no grass for the leaves to catch onto. I ordered the river stones a ton at a time and spread them as I enlarged my no grow areas. The weeds and some grass do come up through the rocks but they are easy to see and pull. I think the layer of stones keep the soil surface as cool as grass would.

I wish I could find that picture I saw...drat it. I thought it was a California garden, but I'm not able to locate it now. It sure was pretty though.

I'm thinking I'll try it and see how it goes. I have the rock on hand, so I might as well. I can't see it holding water longer than soil, so it should be okay.

I have used flat large rocks as mulch around my iris clumps to keep weeds down in my beds. As the clumps grow, I removed the rocks and placed in other areas. Definitely has kept the weeding down.