Hi:
It sounds like a daunting task I must admit, but I think if you either potted them up in big buckets(with drainage), a few to a bucket or planted in the ground they should be OK in your climate. A little freeze shouldn't hurt them. But it looks like you really don't have much choice if you have to move. Iris are tough and they should survive, and they like California and Oregon, so that is a plus in your favor.
Laetitia

if it was me i would just dig them up, lable and store in open flats and then plant when you get to your house in june. they are so no fuss for me i have them out of the ground for 6-9 months when planting back and they still grow. one word of caution, watch out for mice, this summer i did run into trouble with them due to storing too much bird seed nearby. the temptation was great for the them to visit my 1000 iris out of the ground...

I would not worry about leaving them out of the dirt until you are ready to plant in their permanent home. Like jain I have left them in flats, out of the ground for up to 9 months and haven't lost one yet!
Nancy U.

Wow! I would have never thought of leaving them out of the ground on purpose.
Do you think this would only work in a place like California? Where Iris do very well, they would not mind some drying out?
where would you put them? Inside? Outside in a shed unheated?
Laetitia

mine are stacked sky high inside a garage while i plant back, as long as they are not in the sun, any where is fine. i think west coast iris can handle it with the greatest of ease because they grow so large here they are very full of moisture and nutrients. i know if i tired to store a small iris for 9 months i would most likely have nothing in my heat to plant...

I agree with just digging them up and storing until time to replant. My mountain here in Georgia has stray iris all over, growing where I dug them up and discarded them. They have dried up to nothing, yet still put down roots and started to grow. They like neglect.

All of my iris were dug and divided last summer. I had a friend that said she definitely wanted my extras. I had no where to put them, so most were left in the garden in the sun, some in the shade, and finally I collected them all and put them in a pile in the pole barn. Finally, three months later, she came and picked them up. I told her she was welcome to take them, but I couldn't say for sure how they would do. A few weeks later, after she finally planted them, she sent me a picture. They were actually sending up new shoots! I agree with everyone, they can take neglect. I envy you moving to Oregon!

Shadow