irises that don't bloom

I have many iris plants that boomed in the past, but not now. They get at least 1/2 day sun. They are very vigorous, and spread like crazy, but they no longer bloom, Any ideas? What should I use as fertilizer, any thing special???

msmouser

do the ones around it bloom? I have a huge clump of Oh Jamaica, and have had it now 3 or 4 yrs. Never one bloom. It grows like crazy and the iris next to it bloom. I'm so aggravated, I am going to dig it up, and plant another 'start' and wait 2 seasons. No blooms -it's goin to the compost!

I think I read somewhere that if your iris doesn't bloom in two years you should move it to a different spot.

well mine will be packing this summer LOL