For many years I've enjoyed using the colors in one plant to accent a plant nearby. I did it long before it was made popular by Pamela Harper, who wrote a wonderful book about it: https://www.amazon.com/dp/0025481851/

Please post any photos where you've seen color harmony or color echoes. Thanks.

I really liked the color echoes in Fire Dragon Coleus and All Creation Sings daylily. You have to open it to see much of the coleus.

I did enlarge it and saw the coleus - great echoes. It's a joy to spot an unplanned match in the garden.