Rule of thumb: Spring blooming perennials divide in the Fall, late-summer and Fall bloomers divide in the Spring
If you are considering dividing your perennials, do it quickly as the best time to do so is six weeks before first frost (early to mid-October in our area).
Here's everything you need to know about dividing perennials, including how-tos, tips and the pros and cons of dividing.
And an article on how to cut back perennials the right way without risking next year's blooms click here.
Must know tips for dividing iris. https://www.bhg.com/how-to-divide-bearded-iris-11752178?hid=d13d19c359ece750cfb87ef7edc14d2cb4362c77&did=18476464-20250802&utm_campaign=bhg-grow-and-tell_newsletter&utm_source=bhg&utm_medium=email&utm_content=080225&lctg=d13d19c359ece750cfb87ef7edc14d2cb4362c77&lr_input=14d348920b34a351599e98e739857a13375cfb092b41fea1e3ea17665cb27191