That sounds suspicious. People say irises are really susceptible to round-up overspray, so I would be inclined to think Preen might cause the same kind of problems.
Renee

There are (or used to be) 2 kinds of Preen. I haven't bought any lately but there might still be 2 kinds.

If you still have the container, I would be interested to know the active ingredients and percentages printed on the front label.

The kind I use on my non-garden rock mulch has trifuralin 1.47% and the 'vegetable garden Preen' that I was planning to use in my Veggie/Iris beds has corn gluten meal 100%.

Now I am afraid to try it.

I threw away the container when it was all used up. I wasn,t aware there was more than one type. It was the yellow container if that is any help. Next spring I think I will buy more and try it on a small clump that selfstarted by my multch pile to see if it was what caused the problem. If it ever stops raining I will get some pics of the deformed flowers.

If it had a red top it probably had the trifuralin. If it had a blue top it probably had corn gluten meal. I am going to pick a small sample of older iris and try the corn gluten meal on it. We can compare notes next spring.

I wonder if that is what is happening with my bearded iris. Mine look almost like a Siberian iris and the bloom is faded out, like a pastel tint.

Sounds like Round-up or another chemical. That's what happened to mine when I got just a teeny bit of overspray on them. They came back fine the next year.
Renee

corn gluten meal 100%.

can be bought at the feed store for pennies on the dollar as compared the the brand name ...

ken

I have used Preen on several of my beds in the past and have only had problems once. That was when the farmer sprayed a Round up type killer on his field behind the house and got my irises, the garden that we had already put in and even a few planters.