Last year, 36 of my tall bearded irises bloomed. The first one bloomed on October 6th. The last day of flowering was November 17th except for Ring Around Rosie which continued blooming until December 5th. My tall bearded irises gave me 6 weeks of blooming plus a straggler. I also have a few sdbs and intermediates which begin flowering a couple weeks before the talls.
I don't have a lot of space so most of my irises only produce one to three flower stems. They typically flower from 10 to 25 days. It various a lot depending on the hybrid. For example, one stalk of Absolute Treasure flowered for 22 days but one stalk of Ballet Performance flowered for 10 days.
I see the registered bloom seasons of early, mid, late etc as a guide for which irises will bloom first and not as a date range. Irises will bloom on any day and there is plenty of overlap between the bloom seasons.
