Do your flowers fade when the days get hot and the rains recede? I have two low water suggestions for you that take the heat and keep on blooming to help you bridge the floral gap between spring and fall during a hot, dry summer.
Frogfruit is native in the southern half of the United States. It is adaptable to a wide range of conditions. If you don't want it to overrun your garden however, I suggest that you don't add ANY supplemental watering once it is established. Lots of small butterflies and bees are attracted to its diminutive flowers. You can see flower clusters of varying ages in the photo. The longer a flower cluster blooms the taller its base becomes as new flowers are added to the top of the older faded ones. Frogfruit is evergreen to deciduous depending on your winters. Mine is usually deciduous because its leaves are frost sensitive. It makes a nice ground cover and will survive and give you some interest in narrow, hot beds adjacent to pavement where many things will not thrive.
Do you need something that makes more of a statement than a ground cover? Hummingbird bush might be just the thing for you. It does not begin to flower until the temps match the multitude of fiery reddish orange flowers that cover this shrub much of the summer. As the common name implies, hummingbirds love this plant as a nectar source, so you might want to plant one where you can enjoy the show from inside your air conditioned home. More info on this deciduous shrub can be found in my Texas Stars facebook photo album.