Last year our Irises "grew".
Did you cut them back before the leaves turned brown and crispy?
If you leave them untill the fall to cut back they do better,also they might need to be thinned out.
Had you transplanted them from one area to another last year?
Have you used a high nitrogen fertilizer around them? That will promote green growth and not flowers.
Don't fertilize them or when you do fertilize flowers use a bloom food, usually something 0-10-10 or with a low first number compared to the other two. If you are an organic person check out groworganic.com for plant foods.
Another thing to consider is light. Do you have larger shrubs or trees that may have grown and are providing more shade? Irises generally like full sun.
One way to keep them neater looking as the foilage dies back is to use scissors to cut the brown growth off at an angle like the iris leaves are angled. But in general, bulbs, rhizomes and tubers, need to reabsorb nutrients from their foilage to make next years flowers.
No, they weren't transplanted.
Most of our irises bloom both in the spring and in the fall.
I would just try giving them some bloom boost early on the year and I bet that will help. I would have suggested it was because of them being transplantted as that happened to me, but I noticed in further posts you said that was not the case. So give the bloom boost a try and that will probably help. They may be in need of dividing - if they do not flower as well this year I'd divide them this fall and see if that helps. Mine always grow about now (which they're already poking through the yard) and flower about June. Some times it seems really late for them, but they always surprise me.