Answer: Since your site is hot and dry do make sure to add plenty of organic matter when you prepare the planting area so that the soil is able to hold moisture for as long as possible. Mulching your plants will also help reduce the need for water. I can only think of a few perennials that might perform well and look tidy at the same time as being fairly tall, so I have also included a few flowering shrubs to consider. You might try perovskia (Russian sage), purple coneflower, caryopteris (Blue Mist Shrub), dwarf buddleia (Butterfly Bush) or the small, summer blooming spireas. Slightly larger but also pretty are the Rose of Sharon (Hibiscus syriacus) and crepe myrtles (look for the newer smaller varieties if size is an issue). I hope some of these appeal to you.
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