Part 1 of the question:

I have an iris that I'm thinking may be on its LAST year. The reason I think that is because there is just ONE rhizome left and that rhizome has a bloom stalk on it. Is it still possible that it will form increases (none are showing at this time). It has its last bloom on it right now. I will be cutting the stalk off soon. I always cut right down to the rhizome or about 1/2" above. Since I see no increases, should I leave more of the stalk on or does that not matter?
(Crazy for You) This is the one I'm referring to. I like it a lot and hate to loose it.

Part 2 of the question:

When dividing iris, if an increase is of decent size, should I cut the increase away from the rhizome that has bloomed?

If so, what is considered a decent size.

If they are pretty small, is it best to leave the "mom" rhizome attached to the increase?

Sue ~ These are all great questions. Since I really can't give you the answers, we will wait for someone with more experience and knowledge of the subject. I would like to know the answers as well.

It may very well still increase, I'd cut off the stalk just like you always do.

When I divide iris rhizomes, I will often leave at least a chunk of the mother rhizome attached to the increase. That way the cut is on the mother, not the child. If the increases are quite small, I think it's best to leave the mother in tact with the increases, hoping that it helps nourish the increases. No science behind my suggestion, just a gut feeling, you know, like the kind our president uses to make important decisions when he doesn't want to take time to check the facts.

Tom,
Your instinct does make sense. That's what I'll do unless we hear from someone who says "NO NO NO". But I think you're on track.

tveguy3 said:.... you know, like the kind our president uses to make important decisions when he doesn't want to take time to check the facts.

Tom ~ I come to the "Iris World" to get away from "he who must not be named"!

I have always heard that the mother continues to nourish the increases, so I leave the increase attached until it is large enough. The rhizome with the bloom stalk may still produce some new little increases along the sides of the mother so don't give up the ship just yet. If the mother rhizome starts shriveling or gets soft (rot) then toss it.

Last year my Rippling River rhizome produced a bloom and no increases. It finished blooming in the start of November. I noticed that it had no increases in January and added Osmocote. A new offset emerged in early April. It was 5 months from the bloom to the first sign of an offset.

I'm in zone 5a. It should be okay to add Osmocote to my iris now...right? They are just finishing up with their blooming.

I had a beautiful Royston Rubies that had its first bloom although it had two shoots from the original. It bloomed beautifully so I cut the stalk. Well, the other fan just rotted from all of this rain we are having and I was so upset. I put Comet on the bad one and decided it was a goner. A few weeks ago I saw an increase coming on the place where I broke the stalk off!! So there is hope. It keeps growing.

Comet on the rotting rhizome. Is that a good thing to do so it dries up quicker?

I was just thinking the other day and imagined putting Borax on it but didn't have a clue as to what that would do. Help or harm. But if you use Comet without ill effects, I'll use that on mushy rhizomes (after scooping out the mush).

I used antibacterial soap this fall so I wouldn't have to dig up the rhizome...and it rewarded me by blooming and giving increases as well!

Comet with bleach.

petruske said:I'm in zone 5a. It should be okay to add Osmocote to my iris now...right? They are just finishing up with their blooming.

I only add Osmocote to irises that are struggling and have very little or no growth because it has a high ratio of nitrogen in its npk ratio. There are some threads about fertilizing from the past which may be helpful.

The thread "Fertilizing Poll" in Irises forum
The thread "good fertilizer for irises" in Irises forum

Osmocote has a variety of different slow-release fertiliser types available, so it's worth checking the specifics if you want one with a lower nitrogen component than the general one.

Thankyou for the acorn Evelyn

Thanks for the information everyone. Here in Wisconsin I think I'll just cut off the spent stems, clean out any weeds and drying leaves and call it done. Well...until late summer/early fall when I'll clean up more dry leaves and trim the fans.

Totally_Amazing said:Thankyou for the acorn Evelyn

Robin ~ Thank you for bringing us valuable information!