Learn how to read the signs when bearded iris should be divided and transplanted and follow the step-by-step instructions on how to do it. Learn when and how to divide bearded and siberian irises to maintain healthy, blooming plants plus tips for best growing conditions for both iris varieties. · bearded irises are one of the showiest flowers in the spring garden, and they are also one of the easiest to propagate and transplant. Learn how to do it right here. To divide a bearded iris that has started to decline, start by cutting back its foliage by half or even two thirds: · when well cared for, iris plants will need divided on a regular basis. This will reduce its subsequent water requirements as well as transplanting shock. · divide and move the irises in late summer or early fall, after blooming. These tips will help you divide bearded irises like a pro so you can enjoy even more flowers next year. Heres how to divide irises —with step-by-step pictures. · though they are mostly care-free, these irises do need to be divided every three to five years to maximize their blooming potential.