I have learned that daylilies like more water than Tall Bearded Iris. A few years back, I planted a bunch of iris, then a bunch of daylilies in front of them, figuring that when the iris were done, the DL would be starting, and hide the iris foliage. It was great in theory, but I started having problems with the iris later in the summer when their water needs weren't as high, and the DL were.
So last year I dug up those beds, and put the iris in their own beds so I can control the water a bit better. I think Rita has them in mixed beds, but if I remember correctly, her property is terraced, and she has the iris and daylilies on different "levels". ~Jan