The cascading plants will provide a cooling effect and lots of eye-level color. Most local nurseries will custom plant your container, according to Larry Best of TG Trees. Describe the location, the color and effect you want, and they'll do the rest. Accent with non-blooming plants such as licorice and Dusty Miller to show off the blooms. You can also have a handy herb garden in a patio container.
Patio plants are easy to maintain.
Flowers for cutting are near to hand, and weeds are easy to get at with a minimum of kneeling. To care for urns you hardly need bend your back. Feed plants according to directions and you'll have healthy plants well into fall. When summer wanes, transplant any perennials into an outdoor location and mulch well. They should reward you by reappearing the following spring.