Q: I have Siberian irises that need to be divided. Can I do this now? I read that irises should be divided in August, but that seems like a hot time to do it.
A: Siberian iris are almost indestructible. They endure hot dry summers and hard clay soil with equal aplomb. Flowers are in the white-blue-lavender range and the leaves are more grass-like than bearded iris. Like bearded iris, Siberian iris send up foliage and flower stalks from an underground rhizome. Once a plant has been in the ground for several years the center of the clump will become empty with all of the green growth in a circle around it. That’s the signal the clump needs to be dug and divided.
I think the best time to divide is in late winter to mid-spring. There will be plenty of time for the divisions to establish themselves by fall. You’ll likely get blooms from each divided clump in late April but expect more next year.
Iris for the South