Q.Is there a solution that iris bulbs should be washed/soaked after they are divided?
My Aunt had the most beautiful irises. After she dug the bulbs and divided them she washed them with a solution of bleach and warm water but I don’t know the ratio.
Thank you.
Bonnie Myers

Certified GKH Gardening Expert
That is just to ensure that it does not rot in storage. I would recommend a dustable fungicide rather than liquid, though. It can be tricky to use a liquid fungicide and still let it be dry enough to store.
Potassium bicarbonate makes a good fungicide for dusting, as does wettable sulfur (this one is my go-to)
This article will help you with the storage of Iris rhizomes: https://www.gardeningknowhow.com/ornamental/bulbs/iris/storing-iris-rhizomes.htm

Iris borers can bring bacterial rot with them. Dipping rhizomes in a 10% bleach solution is said to help prevent this. Dipping only needs to be done if borers have invaded iris rhizomes. If you haven't encountered iris borers yet, thank your lucky stars.