pbs Digest, Vol 58, Issue 12 I. iberica ssp. elegantissima
Adam Fikso (Wed, 21 Nov 2007 09:27:40 PST)

Good morning, Jim McK. Although it's possible that the rain did the
bloomstalk in, it's unlikely in my experience unless it got flooded and the
area didn't drain.

More likely is a minor injury combined with the wetness you experienced, or
a bit of organic material next to the rhizome. In general these plants
tolerate and can even be greedy for moisture until just before actual
flowering, when one withholds water and even shields it from any rain,
unless it has begun to set seed, in which case more water is tolerated.
However, they are very vulnerable to iris borer, and depth of planting is a
real consideration. They should be high, with the rhizome essentially on
top of the ground where it can not be touched by any organic material. Have
the rhizome itself in the coarsest sand you can find, nearly gravel. A
flat iris bed is likely to prove deadly and the side of a hill is more than
desirable.

Failing these requirements, it can grow well among other plants that take up
any surplus moisture. I had a picture of a really large specimen of this
growing among foot tall grasses near Diyarbekir. (This is the one area of
horticulture that I can claim I know something about. I have only given up
on these after about 45 years.) Good luck.
Adam in Glenvew, IL USDA 5a