The plants arrived in good condition in March. My understanding is that iris are usually planted in the fall (https://www.thespruce.com/how-to-plant-iris-rhizomes-5070514). The rhizomes had lots of roots. I associate iris with surface feeding rhizomes so I dug a 4" trough, laid the fiberous roots in the trough with the rhizome at the end and covered the roots with about 4" of sandy soil and an inch of bark chips. I'll report back on how they survived and grew. I'm curious o see if spring-planted rhizomes survive.