If I split my irisis now because of over crowding, when can I re plant them?
Splitting Up My Irisis
Replant them immediately if you there is to be any hope of bloom later this summer. If you don't care about that, rhizomes may be stored. Here are 2 articles that I hope answer your questions. https://www.gardeningknowhow.com/ornamental/bulbs/iris/dividing-transplanting-iris.htm