Up until this year, I had iris that bloomed in purple and yellow. This year they are all white! I noticed that some of my neighbor’s iris have also turned white, but not all of them. What has happened and will they go back to their original color next blooming season?
The most likely cause of the bloom color change is accidental exposure to an herbicide. Sometimes when we apply weed killer the chemical can drift over to unintended targets. In the case of bearded iris, the exposure can alter the color and shape of the flowers even before they emerge. So we don’t know about the exposure until after the plant blooms.
This chemical drift would explain why all of your iris turned white and only a few of your neighbor’s did. The chemical was probably applied in closer proximity to your flowerbed than hers.
If this is the case, your iris should return to their normal color next year.
Another possibility is cross pollination has created a new iris in the clump that has just this season matured enough to bloom.