Divide at the right time of year, after flowering, when irises become dormant during late summer, reducing the chance of bacterial soft rot. Avoid dividing during winter when irises are trying to survive on stored energy in their rhizomes. Snip the leaf blades to about one third of their height.

What time of year do you divide irises?

Mid- to late-summer is a good time to divide bearded irises. You want to make sure that the roots have ample time to grow before winter. You can usually tell that your irises are ready to be divided when a clump looks overgrown, with rhizomes starting to grow into each other and popping up from the soil.

Can you divide iris anytime?

Bearded iris can be divided any time after flowering; this is often done in July or August in the Midwest so the replanted portions will have plenty of time to develop new roots and become established before freezing weather arrives. Lift clumps carefully to avoid damaging the rhizomes.