Hi,
Many of my favorite daylilies are purples! I've also seen many gardens and some monochromatic plantings of daylilies before. Since purple as a color group tends to "recede", you might want to consider using companion plants on the opposite end of the color spectrum to give a purple bed that "pop" of color. Using exact opposite such as orange or near opposite in color such as yellow would really make the purple and lavender colors stand out. There are many of the newer echinacea ( hardier than the first wave of "designer" echinaceas, most of which died) such as 'Hot Papaya' and others that would make a good color contrast with purple and lavender daylilies. Another long blooming perennial ( the longest blooming perennial here in fact) is Kalimeris. I've grown both white and blue varieties and these begin blooming in June and go right up to frost - white is taller - about 3' with a 3' spread and the blue 'Incisior Blue Star' is short, compact, and good for front of the border. Some of the yarrows come in peach/ apricot tones too. Good luck with your plantings!
