I have never soaked an iris rhizome and personaly know any one that uses that method. Just water them once a week untill new shoots show. If it rains skip the watering.

Mike G

I do the same as Mike except watering weekly. I have heavy clay soil so I do a thorough soaking of the soil and don't water again for a month.

What's your soil like?

Same here, although my soil has pretty good drainage & I still don't water for 3 or 4 weeks after the 1st watering. I don't think it would hurt them either way, as long as the soil doesn't stay wet. Which is exactly what iris gal was saying :)

Thanks for your help. This is the link where I found the info regarding cutting old roots and soaking:
http://www.cdn-iris.ca/pots.html

Though 25 are planted, I have about 400 all total that I will plant this month.

I always soak my iris in a weak bleach solution for 15 minutes before planting, as Walter said in the article.
It is not because they are dry, it is to have the bleach kill anything that may be on them, such as the start of rot.
But if you missed that step before planting, I would not dig them up.