Bright orange crocosmia Fire Jumper, with a flash of blue from clematis Daniel Deronda
Now while you might not see these two plants side by side, what with one being a climber, both colours sing with their association, creating a little more electricity than either of these sparky plants do on their own. Something to remember if your gardening plans seem a little too tame.
Magic.
The Teddington Gardener 
I planted blue Morning Glories to go with orange Tithonia, orange Mexican Sunflower. The Morning Glories are blooming pink! Not what I planned. I was really wanting this color combination this fall. Oh well!