Yes, thats the best time to divide once their finished blooming.

Sharon

I find that after about three to five years that I also need to divide my irises. Dividing and replanting can actually be done anytime in the spring before or after flowering but it is best to do so ASAP after flowering so that you give the iris rhizome long enough to get established in its new home before the winter sets in again.

Here in Manitoba we find that the greenhouses/nurseries order in from BC and usually get a lot of German irises. These only arrive in September and so when planted do not have enough time to establish their root system before our winters set in. I have rarely had a German iris survive in my yard. I always thought it was something I was doing...but just found out after I joined the Northern Lights Iris Society... that it had nothing to do with me, rather it was the weather/short growing season after planting that did it.

There are some excellent articles on the net when you google 'iris dividing' that will show you, with pictures, how to divide and replant each kind of iris.

Brenda

Last weekend, I got a division of Brenda's siberian iris 'Grandis', and was delighted to see the other day, that it's got 2 flower buds coming already. Also, from Marg, I got a piece of dwarf iris that was in bloom at the time. Well, that flower has faded, but 2 new buds have opened up since. I thought that I would have to for go any flowers this year because of dividing them before or during, their bloom, but am quite happy to see that wasn't the case. Iris' are pretty tough customers ;^)

Laurie

Brenda, I had the same experience with the German irises (the Tall Bearded class), and I always thought my gardening skills were to blame. I would buy rhizomes in the fall from local greenhouses, and none of them would be alive the next spring.

My first success with irises occurred when I started getting freshly dug plants from other local gardeners. However, last year I took a chance and ordered some rhizomes from Chapman Iris. Chuck Chapman seems to understand northern garden conditions because he sends out orders earlier for colder parts of the country (if you get your requests in on time).

I ordered several classes of iris from him (from the early Short Dwarf Bearded to the tall, later ones) as an experiment, since it was my first order from his business. I received the rhizomes in late July or early August, if memory serves. Unlike the rhizomes found in fall in local greenhouses, these still had green, live leaves on them.

This spring, all but one of the rhizomes were growing well (and the SDBs have already bloomed). The exeption had been stepped on, and dislodged from the ground, by a deer, and I hadn't noticed this during the winter. However, the rhizome was not rotten, so I potted it up and put it under lights in my basement. It is now sending up leaves, so it will be back in the yard as soon as the rain stops. :-)

Apparently, not all Tall Bearded irises are hardy to zone 3. Chapman indicates, on his site, which varieties are more likely to survive a severe winter. (Other classes, such as SDBs, BBs, are hardier and just as lovely, IMO.)I'm really pleased that I heard about his business from someone else on GW, and I don't hesitate in recommending him to anyone who wants to buy irises by mail order. I'll be a repeat customer, for sure.

Here is a link that might be useful: Chapman Iris