I've found that in my garden, "extra" fertilizer isn't the answer to "save" an iris from bloom out. I've tried several things, and have come to the conclusion that bloom out is LESS likely to occur if the plant is a "bit starved". Especially if there is too much phosphorous , they tend to want to make more stalks / buds, (I'm a big believer in soil tests...add what you need...and no "extra'. As Joe mentioned, if there are no "eyes" on the rhysome....it's a goner. I "experimented" a couple times by cutting a rhysome into "sections" , to see if I could speed up propagation on some especially slow growers....the only ones that grew were the sections that had the "eyes"

Oh! Nice tip which could save quite a bit of time and effort.

My Frank Adams did the same thing. After 3 years of good bloom and not over crowded all the fans bloomed last year and no increase. I had no more FA. I had to acquire another rhizome. I am going to try absolutely no fertilizer as I have a friend who never uses it and her noid is going great guns. If it fails again I am going to assume it just doesn't like its growing conditions and move on to those that do.
Bummer. I really like FA and I do try to grow several historics.

JosephGhio said: Just a word of caution. If the bloom out mother rhizome has no nubbins (bumps) then no amount of fertilizer, watering, cutting the stalk out as it develops and bloom will make it increase. We always let them bloom and when their done, dig it check for nubbins. If none, forget it and dump it and go on to better things.

Thank you so much Joseph. I am so happy to meet you through garden.org. I just bought your "starring", and was amazed by your August post of a white iris. I am so happy to see it registered under the name of "freshly fallen snow". Also really like your "noticeable". I just kook through https://wiki.irises.org/Main/B... and am amazed by the shear amount of irises you introduced. Thank you so much for bring us joy.