I have been under the apparent and now-corrected misconception that I have to continually divide these thugs, and it often just doesn't get done. This information is invaluable to me, and I look forward to rejuvenating my iris beds post haste!

Great information and lovely pictures Kent.

Valuable information Kent -- thank you for posting this.

It makes perfect sense! Thank you for sharing this, Kent. You've helped a lot of people.

fantastic little article. Very informative read.

My pleasure. I think many gardeners have been doing this sort of thing for decades. It's just that the published information on iris culture mostly comes from commercial growers, which makes sense, they're the ones with the most experience. But, commercial growers often dig and replant their entire fields every year or two, a technique like this wouldn't be very applicable.

Muddymitts said:Valuable information Kent -- thank you for posting this.

Maybe I'll start growing Irises again.

Kent, You say you can do this anytime?! (Spring, Summer or Fall)

I never knew that once a rhizome sends up a stalk, that it never does again! I have some clumps that definitely need thinning, not divided Thank you very much for the info.

Wonderful, informative article! I have an ancient clump of iris that came with the place, & are in need of thinning out. Now, where to I get one of those Japanese Hori-Hori knives?

Marilyn said:



Maybe I'll start growing Irises again.

Kent, You say you can do this anytime?! (Spring, Summer or Fall)

Yes, you can do it any time. I like to thin the ones that are crowding their neighbors in the early spring because that is when it's easiest to see what's going on. You have to understand the growth cycle of the plant, though. Thinning in the early spring likely costs some bloom stalks, but usually the ones that are crowding their neighbors will produce plenty anyway.

As I said in the article, we don't have a lot of problems with rot here, but if you do, you'll want to be careful about when you thin. Generally, bearded iris are most vulnerable to rot under hot and humid conditions with saturated soils.

RavenCroft said:Wonderful, informative article! I have an ancient clump of iris that came with the place, & are in need of thinning out. Now, where to I get one of those Japanese Hori-Hori knives?

I bought mine from the Duluth Trading Co., but they can be found in a lot of places. My only recommendations are to buy a real one that was made in Japan, not a knockoff from China, and the ones with stainless steel blades are easier to clean than the ones with carbon steel blades. They aren't cheap, but they will last for decades if taken care of.

http://www.duluthtrading.com/s...

Thanks for the advice & the link, Kent!

Thank you so much for this information! Huge sigh of relief here

RavenCroft said:Wonderful, informative article! I have an ancient clump of iris that came with the place, & are in need of thinning out. Now, where to I get one of those Japanese Hori-Hori knives?

I got mine last year from High Country Gardens

http://www.highcountrygardens....

Thanks Kent!

This method works well for Hosta also. A good way to renew a clump that has grown old and not vigorous in the center.

As an older and disabled gardener, this tip is particularly helpful. Although I cannot stand up to use a shovel, I can certainly sit and use a knife! Thank you so much!

Excellent article, Kent!

Thanks for the info, Kent. Appreciate it very much! Paul

Very timely article! And a lot of information I was not aware of! I didn't realize that the rhizomes wouldn't rebloom either. And I just ordered some new iris for this year for a new spot, so this is wonderful information to have. Thank you so much!