I do that in Fall after blooming or Spring when the leaves are there. Sometimes as they are blooming. Irises seem pretty hardy at my place.

If you do it in the Fall, they have time to establish good roots at their new location and will be more likely to bloom the next Spring. But you won't kill them if you move them at other times. They are tough. They just might not bloom right away.

Susie (the iris fanatic)

Ideally I divide and move bearded iris around aug/sept, the same time most iris nurseries send them out, lots of time to establish their roots before winter sets in, but I have moved some in the spring without any noticeable problems.

Annette

Agreed with all of the foregoing. I have hundreds of irises in my garden from the former owner (who was an avid gardener who left the house at 100 years old). Because of the understandable decline in the work she did in the garden in her last 10 to 20 years, when I took over they were wildly congested mats of rhizomes so I have been doing a lot of dividing for a couple of years now. And I am still not finished!

These things are tough as nails. But I personally think that unless you have a special reason, you do them right after they flower. Why not avoid having to skip a season's bloom by dividing in Spring? The sooner you divide them after they flower, the more time they will have to establish and bloom the next season.

My own approach (though granted I am dealing with a LOT of material) is to be very ruthless and only keep very strong, firm divisions and tossing the rest...anything spongey and/or huge gets tossed in the compost. In my case, this is WELL over half the material. I think this gives stronger, better blooming vigorous stock that doesn't deteriorate nearly so much after blooming, and seem far more able to resist borers.

Dig up the clump, shake off the dirt, and kind of manipulate the clump to pull apart different plants that have grown together. Then take a sharp knife (or pruning shears) to divide up the rhizomes, making sure you get a fan per division. I have been surprised at how small a piece of rhizome, sometimes as small as an acorn, can produce a fan (though bigger is better, especially if you want bloom next year). Sharp, clean cuts.

I almost always cut the leaves with sharp scissors on an attractive angle, about three or four inches up. The big leaves get ratty anyway, and this both minimizes the job the remaining roots have to do, and seems to encourage fresh new (attractive) growth that same season once the roots establish.

I also pull off all old, dead roots. I then give them a through cleaning with a strong spray of water. Replant at the surface (ideally in a nice free-draining amended soil). Firm them in, but you will have to take care for a while as they are just sort of sitting there and are easily dislodged or tipped over until the roots grab hold.

Oh, and by the way (as though my post was not long enough!) if you do them earlier in the season you will have to take special care to keep them watered; but as has been said, they are tough and in my view this extra care is worth it.

Thanks everyone.
I was just wondering if I would lose the spring blooms...
I too have moved them when in bloom with little flower loss.

I have hundreds of irises, as well, all over the garden (one acre garden for all you new to the forum).
I knew all this...just was having a senior moment (omg) I guess. At 58, I guess I am allowed.
(And secretly, I may have just wanted to get back in touch with all my Cottage Gardening friends (wink wink))
But, thanks for all the great info. Loved it!

((HUGS))
~Annie

Annie,
Be careful about that "Senior moment" stuff!!! I'll be 58 too, on the 13th. Glad to see you back on here.

Annie, so good to see you posting here again. Where have you been? We've been missing you..any new pics of your beautiful cottage gardens?