Iris should be divided every 2-4 years. In Colorado, the best time to divide is August. Just dig up the clump, cut the younger, healthier-looking rhizomes away from the rest of the clump, gently wash off the roots of the younger clumps and replant them.

Hi Kristie,

I'll just add that when you replant them, plant them so the rhizome is right on the surface of the soil--just barely exposed. If they're buried too deeply they may not bloom for you. Also, you'll find it easier to handle and replant them if you cut the foliage of each "fan" down short, like 2-4" above the top of the rhizome. Replant them this fall and they should bloom nicely for you next spring.

I have some that need to be dug and replanted too, but don't know when I'm gonna get it done!

Skybird

Thank you. I guess I will plan a weekend in August, then figure out where I'll be replanting. I think it has been about 3-4 years that I originally planted so I guess it's time.

This thread is a good reminder for me, so thank you for starting it Kristie! It is way past time for me to divide my Irises as well, so I am going to put it on my already-much -too-long-but-still-constantly-growing "To Do" list.

Sadly, some of my Irises were killed this spring. Many of those in my backyard were actually underwater or in thoroughly saturated soil for much of the month of May and into June, despite my efforts to pump out the standing water, because of all of the rain we had here. Needless to say, the rhizomes just rotted in the ground. :-( Only good thing about this, is that it means there is now plenty of room to spread out and replant the divided Irises from elsewhere in my garden.

Holly

Hi Kristie, I, too, live in COS and divided all of my irises last year. This year only a few flowered, but their leafage has increased exponentially, so 2016's crop should be beautiful. A neighbor divided her irises and they blossomed straightaway. Perhaps I buried them too deeply? Anyway, bury deeply or not, you'll be getting beautiful irises soon, but maybe not the year afterward. Best, Kristen