Color, pale or intense, can be caused by weather, with some cultivars more susceptible than others.

Your other colors have not yet grown rhizomes large enuf to bloom is a possibility.

Your foliage is big and healthy ~~ have you fertilized with a high nitrogren fertilizer which feeds foliage at the expense of bloom?

It sounds like one variety of iris has taken over your bed at the expense of the other colors. Have you divided them yet?

Hi yes thank you
I have divided.
They all bloomed beautifully the first year,
Then last year and this year all pale yellow.
WE have had 8 inches of rain last month,
and 2 already this month.
I am on sand so Id think they are draining ok.
I did notice today tho one is going to be white.
Thank you everyone.
Dianne