Click below to listen to my Garden Bite radio show: Dividing Iris
Overcrowded iris? If you saw less flower production and the rhizomes are coming completely up out of the ground, then you might want to divide them!
Iris should be divided every 3 to 4 years. First cut the foliage fans back to about 3 to 6 inches. Remove any yellow or dead leaves. Gently dig out the rhizomes. Cut them with a sharp knife leaving them each about 3 to 4 inches long. Remove any mushy parts, hollow tubers or those that may have grubs. If you’ve had fungal issues, treat the rhizomes with a fungicidal powder before replanting. Use a 10% bleach solution after each cut.
To replant loosen the soil to about 8 inches, leave about 2 inches of roots and give them room… plant the rhizomes so that they are just barely under the soil. Don’t mulch! This sounds counter-intuitive but irises need a dry period. AFTER the ground has frozen you can mulch to prevent heaving.
If your irises are just fine, then leave them alone. Let them die back on their own. For more detailed information on all things Iris click HERE [Univ. of MN Ext]
Have you tried Reblooming Iris? They will bloom intermittently from midsummer to frost. Check your local garden center for rebloomers! I’m seeing sales on them now through mail order…
This link to Breck’s Bulbs is quite a teaser on reblooming bearded iris!