Several things could have happened to your iris:

1) They could STILL be too crowded with not enough room for increase even though you did divide them.

2) The place where they are located could gradually have become shadier. Iris like lots of sun.

3) The soil might be tired and in need of more nutrients.

4) You've had extraordinaryily bad weather for 4 years in a row. NOt likley, I know. But, we had 2 years in a row of bad weather. But in that 3rd year, dang, the iris bloom was fantastic!

5) When you replanted, you planted them too deeply.

If your iris were strong bloomers before you divided them, and assuming the rhizomes are still firm and strong and producing big leaves, one of hte other factors I listed above is the culprit. PRobably. :) But that's why I love iris, they are so exotic and can be difficult to coax into bloom.

No. May need to dig the clump and thin to a handspan apart. Feed them in late summer when foliage has again begun to grow. Make sure they have plenty of sun.

One more possibility. When did you divide them?

Some iris varieties are finicky about division, especially if not at the perfect time. They may refuse to bloom the first year after a division.

Unless you amended the soil that is probably the major culprit. Low nitrogen fertilizer only.

The other factor not popularly shared is the slowness of some cultivars to re-establish after division. Often pooh-poohed by people who have experience with older ones that accept poor conditions/treatment and continue to bloom. But some newer introductions can easily take 2-3 years.

When you divided you may have found some dried out husks od old rhizomes. A rhizome blooms once then produces babies which in turn grow to blooming size. Be patient.

miss iris_gal:
how do we in the iris world become patient ? - this is an addiction - i go out to the garden at least twice a day to count the bloom and diligently peruse each plant for evidence of other blooms

patience - i need counseling :)

mr toad

Be patient.

I moved buckets of Indian Chief, a hardy historic iris, from an old building one summer;
they didn't bloom at all the next spring, a few bloomed the following spring, & this year they've burst into flower all over the gardens.