Bearded iris do not sport like roses. They do not change colors like hydrangeas. Each new rhizome growing off the mother rhizome is an exact genetic match. It will branch and bloom exactly like its mother rhizome.

Purples are usually very aggressive growers (heredity). Some cultivars may produce 8-12 babies (off one mother rhizome!). And in the same soil an apricot may produce only 2 babies. Over the years the purple takes over, traveling into the area originally planted with another color.

I had a lovely, named, pale pink bloom beautifully the year after planting. By itself with roses and salvia. No babies! Not one. Had it been near other beardeds I wouldn't have noticed.

In a full patch the only sure way to remove the color you want is to dig out while in bloom or tag the blooming stem and dig right after bloom, getting the rhizome from which the stem has arisen.

So disappointing after all your work. Now you know you have an extremely vigorous purple which will take over. Her's a picture of my aggressives grower.

I do not like mixing same plants with different colors, period. I always plant them in separate beds.

I grow like 700 daffodils. There are about 200 mixed white and yellow. It is not my favorite. I may get rid of them when I have more divisions to do with the pure white and pure yellow ones.