We don't have a specific document that addresses flower garden design, but we have several publications that provide information on design and on plant material. One publication, Master Gardener's Manual, does cover flower garden design in Chapter 6, Part 2: Herbaceous Ornamentals. Many other publications on plants that grow well in Oklahoma can be found on our publication site - https://extension.okstate.edu/fact-sheets/.

A couple resources that may be helpful are the Oklahoma Proven Plant Selection Program, https://extension.okstate.edu/programs/oklahoma-proven/, and Water-Efficient Landscapes for Oklahoma.

Hope this helps. You can also reach out to your Wagoner County OSU Extension Service for additional assistance. https://extension.okstate.edu/county/wagoner/