I'd be careful about soaking, in my experience there is a period when a rhizome is very susceptible to rot just before it starts active growth. It may be a good idea to do a brief soak (10 minutes) in a mild bleach solution (1 part household liquid bleach to 10 parts water), which will kill some of the disease bacteria. Then pot them in 4" pots on sterile potting mix. Water sparingly until the first growth is evident. They can be planted out as soon as the roots have reached the bottom of the pot.

This method is how I treat any 'challenged' rhizomes - for example starting a leafless mother from a potential bloom out. When I got Iris from Australia I did this also to help with the seasonal crossover.

Chad

In August 2010 I received iris rhizomes in a swap. I opened the box and planted the iris (They were wrapped in newspapers when I received them in the mail). I put the box with the newspapers in my utility shed. Last May (8 months later) I wanted to reuse the box to ship something else. I found an iris rhizome wrapped in newspaper. I planted it and it grew.

You can see the green in back of the dried foliage a week or 10 days later.

Don