It is difficult to plant flowers with lots of color that will actually survive in the extreme Arizona summer heat. Below are a few that tend to fare well and will work in containers.
Vinca – a summer favorite. These will do well in full sun to partial shade. They need water daily in extreme temperatures and will bloom from spring until frost. This is my favorite Arizona Summer Flower for all summer bloom.
Celosia – this is a flower that I don’t have much experience with but plan to plant it this summer. This flower is very hardy and likes the sun. They come in different varieties such as the New Look or China Town.
Portulaca – this is fast growing ground cover type of plant. They love the sun and blooms all over the plant.
Here is a link to a great guide on what to plant and when: Flower Planting Guide for the Low Desert