There is no hard and fast rule because different rzs and different cultivars respond differently. Some bloomed rzs won't produce increases at all. Most will produce some increases. Some will continue to produce additional increases after being separated from the first round of increases. But there are no guarantees one way or the other.

My guess is that the slices you replanted yesterday probably won't survive. Theoretically if the mother rz is still viable, and if you cut her into chunks that contain growing points and enough mass to support both the original chunk and the development of new increases, and IF the cut surfaces don't rot, the replanted chunks *might* grow increases. However, cut surfaces are especially susceptible to invasion by erwinia bacteria that is endemic in most soils and will cause your slices to rot. That's why it is recommended that newly divided irises be allowed to dry and their cut wounds to scab over for several days before replanting.

It'll be interesting to read the results of your experiment. You just never know what an iris will do.

Laurie

'Potato Slices'? How thick? A slice to me is something no more than half an inch thick...if so, they won't grow.
However, a 'slice' may mean something different to you.
I would think that anything less than about 1.5 inches is a waste of time.
If you want to experiment with old mothers, try to keep them intact, or cut in half, dry out the cut end for a day or two then replant.
I have heard people say that either 'nicking' a mother might stimulate it to grow, or watering it with 'willow water' (water where willow cuttings have been stuck for a few days) may help stimulate new growth.
Laetitia

There have been discussions of propogating irises this way to get increase faster so the iris can be put on the market sooner. I have never done it.

This subject can be found discussed in the Mallorn Archives.
I don't remember what year(s). You can Google Mallorn Computing and find it.

Walter Moores

I sliced up the poor dears with just about a half inch. Guess I killed them!

This morning I checked some of my old mothers and a clearly 3 year old one has a tiny baby coming out.

And there is hardly any room but there it is. Several more as well.

I bought some mothers on ebay and while they did multiply they have not bloomed. I think they will this year though -- finally!

thanks guys. Esp you laurief.

I guess the ladies like the mystery of why it is they do what they do....or don't do....

I'm curious about the willow water. I have a willow tree (corkscrew willow) that always needs suckers cut off. What kinds of things can you use this on? What situations?

linnea:
I just know that willow has some kind of growth hormone, and if one wants to take a cutting of a woody plant (tree or bush), if they stick it in water with some freshly cut willow it will encourage root growth on the other plant. I have heard of someone using willow water to soak an old mother and new increase appeared. However, I tried it once on a very beat up old mother and it did not work.
Mccommas: Please let us know if the potato slices work for you. I don't think they will, but would be interested in hearing what happens..
Laetitia