A garden dressed in jewel tones sparkles like no other. In my landscapes I contrast deeply saturated hues with foliage plants. For example, this photo illustrates Impatiens 'Blue Bayou' mixed with the broad, green leaves of hosta and the whitish cast of Japanese Painted Fern.
You could also plant coneflower (Echinacea). It is a summer flowering perennial and comes back every year.
|Echinacea by Howker|
I also love the clear colors of deciduous azaleas, specifically the Northern Lights hybrids. Here is 'Apricot Surprise' - a Northern Lights hybrid. Plants are 4 feet tall with doubled flowers of a distinct apricot-peach tone. This planting is in a wooded area and is set against a leafy green backdrop. This makes all the difference when you want a color to pop out! It's not so much the color as the effectiveness of the background.
Even autumn leaves can be a colorful palette. Like in this photo below.
So consider using jewel tones in your garden this year! Btw, I have a whole chapter about color in the garden in my book, "Heaven is a Garden" .