Let dry out or not?

[cheops]

I have several ceramic pots of irises which after showing a marvellous display with their flowers, now the flowers are fading. I want to lift these bulbs and plant them in the autumn in a permanent site in the ground. I know the leaves should be allowed to die back fully before lifting the bulbs as one should do with any flowering bulb.
However my question is do I need to keep the soil in the pot watered and moist till the leaves have rotted away or can I let the pot dry out in a shed or somewhere as the leaves die back? Anyone who can advise on this?

[roitelet]

Keep watering until the leaves begin to turn yellow and then dry out the pots. The leaves feed the bulb for next year.