It could be freeze damage or it might be the result of herbicide poisoning. Any chance that the iris may have been hit with some RoundUp or RoundUp drift?

In any event, chances are that the plant will bloom normally next year if it doesn't fall victim to similar climatic or chemical difficulties.

Laurie

The herbicide sounds the most likely as I have had some very stubborn weeds that don't pull up easily and I resorted to using Roundup . Thanks. I'll hope for the best.

I posed almost the exact same question last year. I thought it was a virus since I had planted some new rhizomes in the affected area--and it hit on one of my prized well-established plants.

Someone suggested "Round-Up" drift. Bells started to ring and I'm pretty sure that that was my culprit.

This year the plants are looking great....and I've learned NEVER to use Round-Up until after the bloom season.

GOOD LUCK!!!!

When I need to apply an herbicide is a tight spot I use my handy dandy isolation can. A large size coffee can with the top & bottom cut out. Place it over the offending plant and spritz away. But then you have to wait until the foliage dries and make sure that it won't actually touch. This does have some limitations in where you can use it.