Once the rhizomes are free of soil, rhizomes will snap off easily. Or, you may want to cut them off with a knife. Do not save any rhizome without green leaves. If you plan to replant only a few plants, choose the largest ones. Smaller plants also may be kept, but if they are immature, do not expect them to bloom next spring.
Irises are good drought-tolerant plants once they are established.
You should plan on watering your newly set plants about every two to three days until you see three or four new leaves emerging from the center of the plant. By then the weather will have cooled, and you can water less frequently. Irises will respond to a deep drink of water every seven to 10 days instead of a light sprinkle every day. Iris roots go down deeply, and you want to get the water to where the roots are. If you have mature clumps, you can get by with watering every three to four weeks in the summer if you soak them deeply each time.