Both are very nice!
Pamela Harper has made color harmony popular in the gardening world in her book, available at Amazon and many used book dealers online:
https://www.amazon.com/dp/0025481851/
COLOR ECHOES: The author of this book pioneered the concept of colour echoes, a method of creating colour harmonies in the garden. Echoes are simply the repetition of different tints of one colour throughout a garden, resulting in overall unity. Starting with a sharp look at standard colour theory and why it doesn't work, the author outlines the basics of echoes and what they accomplish, from accentuating subtle colours to toning down harsh ones. This is followed by a discussion of the use of specific colours.
Echoes is repetition whether through another plant, a flower, garden art, shapes, etc. There's more on it here (and some of my photos):
https://www.amazon.com/dp/0025481851/
Harmony, just like in music, is a pleasant combination.
