Just a question about mother rhizomes--do you need to plant the entire rhizome or can you cut it into multiple pieces and have them grow? When I uprooted that huge mess of white bearded iris I noticed some tiny increases on several mother rhizomes. I had so daughter pieces that I just threw away all of the mothers that were well removed, wouldn't change that since I had 2 big tubs of nice sized new growing pieces to give away even after I replanted the entire bed. I'm dividing some more colorful iris today (if the weather clears) that aren't in huge clumps so I want to optimize the growing potential. I won't be trading off/giving away any mother pieces, regardless of increases, just wondered if I should leave them in as big of a single piece as possible or if dividing the rhizome would stimulate more/better growth when I replant. I will remove any parts that are mushy or rotted looking, of course.

I have better luck planting the whole Mother rhizome.

A few years back, I believe Arlyn (@crowrita1) did an experiment on cutting up a rhizome in hopes getting more sprouts on rare irises.

That's what I did, figured better safe than sorry! Got around 10 clumps divided and had 4 mothers that I pulled apart from the juveniles and replanted, they were on Raven Girl, Superstition, Champagne Elegance and Laced Artistry. There were several with mothers that I left with the new growth because the roots on the new part didn't looks substantial enough to keep the division grounded. Divided severely enough that I shouldn't have to touch those again for several years! Still have several to do on Friday before Sunday's trade.